Electric chainsaw

Abstract

Electrically powered chainsaw (10), comprising a main body housing (11) accommodating an electric motor (23) powered by a rechargeable battery, a guide rod (21) which is fixed at its base end to a side portion of the main body casing (11) and projects forward, a saw chain (22) which is stretched around the outer circumference of the guide rod (21) and is driven by the electric motor (23), a rear handle (13) extending rearwardly from a rear portion of the main body housing (11) and held by the operator, and an arcuate front handle fixed at its left and right lower end portions to both sides of the main body casing (11), wherein the electric motor (23) is started by an operating switch on the rear handle (13), wherein a set of compact, general-purpose battery packs (31) which are also usable for electrically powered working devices such as electrically powered tools, electrically powered gardening equipment or the like is used as the rechargeable battery, wherein the main body casing (11) comprises on the left and right sides at the rear portion of the main body casing (11) an attachment portion (25) for each battery pack (31) of the set of battery packs (31) to be attached, wherein the attachment portion (25) comprises a pair of guide rails (25b) extending in the vertical direction, wherein the battery packs (31) of the set of battery packs (31) are configured to be vertically slidable along the guide rails (25b), and wherein the set of general-purpose battery packs (31) is attached to the rear portion of the main body casing (11) such that a center of gravity (G) of the chain saw (10), when the battery packs (31) of the set of battery packs (31) are attached to the attachment portions (25), is located in an area (R) that is 1.5 times a width (W) (30 mm) of a grip portion (13a) of the rear grip (13), on the left and right sides of a vertically extending center line (C) centered in the left-right direction, and wherein left and right attachment portions (25) for the battery packs (31) are arranged mirror-symmetrically to the center line (C).

Description

Technical field

[0001] The present invention relates to an electrically powered chainsaw that uses a rechargeable battery pack. General state of the art

[0002] JP 2010-201612 A discloses an electrically powered chainsaw. This electrically powered chainsaw includes a main body housing housing an electric motor powered by a rechargeable battery, a guide bar having its base end fixed to a side portion of the main body housing and projecting forward, a saw chain (sawtooth chain) stretched around the outer periphery of the guide bar and driven by the electric motor, a rear handle extending rearward from a rear portion of the main body housing, and an arcuate front handle having its left and right lower end portions fixed to both sides of the main body housing. The rear handle includes an operating switch for starting the electric motor.To operate the chainsaw, the operator holds the rear handle with their right (or left) hand and a side handle with their left (or right) hand. With a finger of their right (or left) hand, they operate the trigger switch to engage the electric motor. This causes the saw chain to rotate around the guide bar, allowing the operator to cut wood.

[0003] DE 202013 102 567 U1 discloses a mobile electrical device, in particular a hand tool, gardening tool or hand-held garden tool, with an electrically operated drive motor for rotating, oscillating and / or revolving tool carriers or processing tools, the electrical energy supply of which comprises at least two lithium-ion batteries of the same design and largely the same capacity and nominal voltage, which are electrically connected in series and to which separately operating monitoring devices for the permanent monitoring of electrical and / or physical parameters such as current voltages, currents and / or temperatures at the individual batteries are assigned, which are coupled to a protective circuit,which, at least in the event of undervoltages and / or overtemperatures, provide for a voltage and / or current limitation and / or a separation of the affected accumulator(s) from other electrical components of the electrical device.

[0004] US 2014 / 0 054 054 A1 discloses a battery-powered chainsaw. The chainsaw may include various components, such as a control board with a controller, a battery terminal block, a motor, a brake switch, a trigger switch, and / or other components. In various embodiments, components of the battery-powered tool are provided that enhance the capabilities and / or operation of the tool.

[0005] Furthermore, battery-operated power tools are disclosed in JP 2010-201 612 A, EP 2 340 916 A2, EP 2 223 780 B1, CN 202 367 273 U, DE 196 17 157 A1, US 2010 / 0 095 537 A1 and DE 10 2009 012 178 A1. Summary of the inventionObject of the present invention

[0006] The electric chainsaw described above incorporates a large battery pack with a high rated voltage (e.g., 36 V) to power the high-output electric motor. A large battery pack of this type with a high rated voltage is primarily limited to electric chainsaws and is also expensive. Its universal applicability is limited, while also imposing a significant financial burden on the user. However, in the technical field of electric tools, gardening equipment, cleaning equipment, etc., a compact, general-purpose battery pack with the same rating has been developed.

[0007] In view of the above-described situation, it is an object of the present invention, in an electric-powered chain saw in which a battery power source composed of a set of compact, general-purpose battery packs of the same rating is used instead of the large battery pack with a high rated voltage conventionally used for an electric-powered chain saw, the set of general-purpose compact batteries is mounted at a suitable position on the main body casing so that the operability of the saw chain is not impaired. This object is achieved by means of the electric-powered chain saw according to claim 1. Preferred embodiments are set forth in the dependent claims.

[0008] An electrically powered chain saw is disclosed, comprising a main body housing an electric motor powered by a rechargeable battery, a guide rod having its base end fixed to a side portion of the main body housing and projecting forward, a saw chain tensioned around the outer periphery of the guide rod and driven by the electric motor, a rear handle extending rearwardly from a rear portion of the main body housing and held by the operator, and an arcuate front handle having its left and right lower end portions fixed to both sides of the main body housing. The electric motor is started by an operating switch on the rear handle. A set of compact, general-purpose battery packs is used as the rechargeable battery.wherein the set of general-purpose battery packs is mounted on the rear portion of the main body casing such that a center of gravity G of the chainsaw is located in an area R which is 1.5 times a width W (30 mm) of a grip portion of the rear grip, on the left and right sides of a vertically extending center line C centered in the left-right direction.

[0009] In the electric chain saw configured as described above, by disposing the battery pack set at the rear portion of the main body casing such that the center of gravity G of the chain saw is offset in the left-right direction on the left and right sides of the vertically extending center line C centered in the left-right direction in the area R that is 1.5 times the width W (30 mm) of the handle portion of the rear handle, the main body casing is slightly inclined in the left-right direction, thereby improving the operability of the saw chain. When the offset of the center of gravity of the battery pack set to the left and right from the vertically extending center line C centered in the left-right direction of the handle portion is the same, the weight balance of the left and right sides of the main body casing is improved.

[0010] In the electric chain saw of the present invention, the set of battery packs is mounted in a parallel arrangement on the main body case, which makes the battery packs easy to attach and detach.

[0011] In the electric chain saw of the present invention, when the set of battery packs is connected in series, the electric motor can be used with high output power, and when connected in parallel, the electric motor can be used for a long time. Short description of the characters

[0012] They show: Fig. 1 is a perspective view of an example of an electrically powered chainsaw not covered by the claims; Fig. 2 a top view of the chainsaw Fig. 1; Fig. 3 a right side view of the chainsaw Fig. 1; Fig. 4 a rear view of the chainsaw Fig. 1, which illustrates the center of gravity of the chainsaw when viewed from behind; Fig. 5 a right side view with the battery pack removed; Fig. 6 a perspective view of the battery pack; Fig. 7 a sectional view along AA from Fig. 6; Fig. Fig. 8 is a rear view of a first modification example; not covered by the claims; Fig. 9 is a rear view of a second modification example; not covered by the claims; Fig. 10 is a right side view of a third modification example according to the invention; Fig. Fig. 11 is a right side view of a fourth modification example; not covered by the claims; Fig. 12 is a right side view of a fifth modification example; not covered by the claims; Fig. 13 is a right side view of a sixth modification example; not covered by the claims; Fig. 14 is a right side view (a) of a seventh example not covered by the claims but useful for a better understanding of the invention, wherein (b) is a right side view with the rear portion of the main body casing rotated; Fig. 15 is a right side view (a) of an eighth modification example not covered by the claims, wherein (b) is a right side view when the rear portion of the main body case is rotated; Fig. 16 is a right side view of a ninth example not covered by the claims but useful for a better understanding of the invention; Fig. 17 is a right side view of a tenth example not covered by the claims but useful for a better understanding of the invention; Fig. 18 is a right side view of an eleventh example not covered by the claims but serving to better understand the invention; Fig. 19 is a right side view of a twelfth modification example; which is not covered by the claims; and Fig. 20 is a right side view of a thirteenth modification example; which is not covered by the claims. Best way to carry out the invention

[0013] In the following, an embodiment of an electrically driven chain saw of the present invention will be described with reference to the accompanying figures. As shown in Fig. 1 to 3, the electric chain saw 10 includes a main body case 11, and an elongated guide rod 21 is provided at the front portion of the right side surface of the main body case 11 to project forward. The rear portion of the guide rod 21 is covered by a sprocket cover 12 provided at the front portion of the right side surface of the main body case 11, and the remaining part of the guide rod 21, except for the rear portion, projects forward from the main body case 11. A loop-shaped saw chain 22 is circumferentially mounted on the outer periphery of the guide rod 21. The saw chain 22 is circumferentially tensioned around the guide rod 21 and a sprocket 24 rotatably mounted immediately behind the guide rod 21.Several sawtooth-shaped cutting edges are provided in succession on the saw chain 22, and as the saw chain 22 runs around the guide bar 21, the saw teeth move continuously around the outer circumference of the guide bar 21.

[0014] As in Fig. 2 and Fig. 3, an electric motor 23 is housed at the front inside the main body case 11, and the electric motor 23 rotates the saw chain 22 on the outer circumference of the guide rod 21. An output shaft 23a of the electric motor 23 projects inside the sprocket cover 12, and the sprocket 24 is fixed to the output shaft 23a. When the sprocket 24 is rotated by operating the electric motor 23, the saw chain 22 rotates around the outer circumference of the guide rod 21 by the rotating sprocket 24.

[0015] As in Fig. 1 to 4, a rear handle 13 extending rearward is provided at the rear portion of the main body casing 11, and a front handle 15 is provided centrally in the longitudinal direction of the main body casing 11. The rear handle 13 has a U-shape, tilted to close the rear side, when viewed from the side, and the upper portion of the rear handle 13 is a grip portion 13a held by the operator. A cross-sectional shape of the grip portion 13a of the rear handle 13 in a direction intersecting the longitudinal direction is substantially round, and a width W of the grip portion 13a in the left-right direction is 30 mm, thus being suitable for one-hand holding. The length of the grip portion 13a in the left-right direction may be in a range of 25 mm to 40 mm, suitable for one-hand holding.An operation switch 14 is provided on the underside of the front portion of the grip portion 13a of the rear grip 13, and the electric motor 23 is operated by pushing the operation switch 14.

[0016] As in Fig. 1 to 4, the front grip 15 has an approximately U-shape that is splayed downwardly above the longitudinally central portion of the main body case 11, and both longitudinal end portions of the front grip 15 are fixed to the two side portions of the main body case 11. In the front grip 15, a central portion constituting the top of the main body case 11 is a grip portion 15a held by the operator. The front grip 15 has an approximately U-shape with the bottom opened, but it is not limited to this and may also be O-shaped.

[0017] As in Fig. 1 to 4, a battery source 30 that supplies power to the electric motor 23 is detachably attached to the rear portion of the main body case 11, the battery source 30 of this embodiment comprising a set of battery packs 31 including two battery packs 31 arranged in a row on the rear portion of the main body case 11 on the left and right sides. Fig. Fig. 5 is a right side view of the main body casing 11 with the battery packs 31 removed, wherein two mounting portions 25 for mounting the set of battery packs 31 comprising two battery packs 31 are provided centrally at the rear portion of the main body casing 11 (in Fig. 5, only the right attachment portion is shown, while the left attachment portion, which is mirror-symmetrical to the right attachment portion, has been omitted. The two attachment portions 25 are provided centrally at the rear portion of the main body case 11, adjacent to each other. The attachment portions 25 are provided in the same number as the battery packs 31.

[0018] The attachment portions 25 have terminal portions 25a that can be detachably attached to an electrical terminal 34 on the battery packs 31. The terminal portions 25a are electrically connected to the electric motor 23, and when electrically connected to the electrical terminals 34 of the terminal portions 25a of the battery packs 31, the electric motor 23 is electrically connected to the battery packs 31. A pair of guide rails 25b consisting of left and right guide rails is provided on the left and right sides of the terminal portions 25a and extending in the vertical direction, and the battery packs 31 are attached such that they can be slid vertically along the guide rails 25b. An inwardly indented locking portion 25c is formed at the upper portion of each attachment portion 25, and a hook 36 provided on the battery pack 31 can be engaged with the locking portion 25c.By engaging the hook 36 of the battery pack 31 into the engaging portion 25c of the attachment portion 25, the displacement of the battery pack 31 on the guide rail 25b of the attachment portion 25 is restricted.

[0019] The battery packs 31 serve as the battery source of the electric motor 23 and are rechargeable using a charger (not shown). The battery packs 31 are a universal power source that can be used for various types of electric tools or electric gardening equipment. The rated voltage of the battery packs 31 of the present embodiment is 18 V, and they can be widely applied to various types of power tools or electric gardening equipment. In this embodiment, two battery packs 31 are connected in series with the electric motor 23 and used as a 36 V power source.

[0020] As in Fig. 6 and Fig. As shown in Figure 7, a battery pack 31 includes an approximately cuboid-shaped casing 32, and ten columnar battery cells 33 are housed inside the casing 32. The direction in which the battery pack 31 is attached to the attachment portion 25 by sliding is the longitudinal direction of the casing 32, and the battery cells 33 are housed in a direction in which their axial direction intersects the sliding direction for attachment to the attachment portion 25. The position of the center of gravity Gl of the battery pack 31 is approximately at the center of the casing 32.

[0021] An upper wall (peripheral wall) of the housing 32, which Fig. 6 is a wall surface facing the attachment portion 25, and on the upper wall of the housing 32, the electrical connector 34 is provided, to which the connecting portion 25a of the attachment portion 25 can be detachably attached. As mentioned above, the electric motor 23 is electrically connected to the battery pack 31 by connecting the connecting portion 25a of the attachment portion 25 to the electrical connector 34. Fig. 6, a pair of rails 35 extending in the longitudinal direction is formed integrally on the upper wall of the housing 32. The pair of rails 35 are arranged in a direction orthogonal to the longitudinal direction of the housing 32 on both sides of the electrical terminal 34. The hook 36 is attached to the Fig. 6 shown upper wall of the housing 32 projecting towards the top (the side of the attachment section 25), wherein the hook 36 is urged by a spring element 37 to the position shown in Fig. 6 (the side of the locking portion 25c of the attachment portion 25).

[0022] When the hook 36 is engaged with the locking portion 25c of the attachment portion 25 in a state where the attachment portion 25 is attached to the battery pack 31, the electrical terminal 34 of the battery pack 31 is electrically connected to the terminal portion 25a of the attachment portion 25, and the movement of the battery pack 31 along the guide rail 25b is restricted. When the hook 36 is retracted from the locking portion 25c by means of a release button 36a against the biasing force of the spring member 37, the battery pack 31 can be slid along the guide rails 25b. When the battery pack 31 is slid along the guide rails 25b in this state, the electrical connection of the electrical terminal 34 of the battery pack 31 to the terminal portion 25a of the attachment portion 25 is released, so that the battery pack 31 can be detached from the attachment portion 25.

[0023] As in Fig. 2 and Fig. 3, a control device 26 is provided inside the main body case 11 for controlling the power supply of the electric motor 23 by the battery packs 31 and the operation of the electric motor 23, the control device 26 being arranged at a position near the position where the attachment portions 25 are provided, below the attachment portions 25.

[0024] In the chain saw 10 configured as described above, when the grip portion 13a of the rear handle 13 is held with the right hand and the grip portion 15a of the front handle 15 is held with the left hand, and the operating switch 14 on the front portion of the grip portion 13a is operated with the index finger of the right hand, the electric motor 23 is powered by the two battery packs 31 and operated. When the sprocket 24 rotates by operating the electric motor 23, the saw chain 22 rotates around the outer circumference of the guide bar 21. In this state, when the saw chain 22, which rotates around the outer circumference of the guide bar 21, is applied to a wood material such as a log, the wood material such as the log is cut by the saw chain 22 rotating around the outer circumference of the guide bar 21.

[0025] In the chainsaw 10 configured as described above, a set of battery packs 31 including two rechargeable battery packs 31 applicable to various types of electric tools or electric gardening equipment are used for the battery source 30 that supplies power to the electric motor 23. Therefore, by using battery packs 31 that have high universality with applicability to electric tools or gardening equipment as the battery source of the chainsaw 10, a user does not need to prepare battery packs of different ratings (e.g., different voltages) for the chainsaw 10, electric tools, or gardening equipment, thereby increasing user convenience.

[0026] Furthermore, the center of gravity G of the chainsaw 10 is mainly determined by the position of the heavy electric motor 23, the position of the guide rod 21, and the equally heavy set of battery packs 31, comprising two battery packs 31. If the position of the center of gravity G of the chainsaw 10 is unsuitable, this will impair operability. As shown in Fig. 4, the set of battery packs 31 comprising two battery packs 31 is arranged at the rear portion of the main body casing 11 such that the center of gravity G of the chain saw 10, when viewed from the rear, is located in an area R that is 1.5 times the width W (30 mm) of the grip portion 13a of the rear grip 13, offset in the left-right direction on the left and right sides of the vertically extending center line C centered in the left-right direction. Therefore, when the chain saw 10 is held by the grip portion 13a of the rear grip 13, the main body casing of the chain saw 10 does not easily tilt in the left-right direction, and therefore, it is not necessary to hold the grip portion 13a particularly tightly, so that the operator is less likely to become fatigued.The center of gravity G of the chainsaw 10, when viewed from the rear, is located in the area R that is 1.5 times the width W (30 mm) of the handle portion 13a of the rear handle 13, on the left and right sides of the vertically extending center line C centered in the left-right direction, and is slightly shifted to the right from the center line C. In this way, the main body of the chainsaw 10 is slightly tilted to the right (in the left-right direction), whereby the operability of the chainsaw 10 can be improved.

[0027] The centers of gravity G1 of the two battery packs 31 of the set of battery packs 31 are located in the area R that is 1.5 times a width W (30 mm) of the grip portion 13a of the rear grip 13, on the left and right sides of the vertically extending center line C centered in the left-right direction. In addition, the centers of gravity G1 of the two battery packs 31 of the set of battery packs 31 are distributed on both sides of the vertically extending center line C centered in the left-right direction of the grip portion 13a (the left and right sides). Therefore, when the operator holds the chain saw 10 by the grip portion 13a of the rear grip 13, the left-right weight balance is improved, and therefore, it is not necessary to hold the grip portion 13a particularly tightly, so the operator is less likely to fatigue.

[0028] In this electric-powered chain saw 10, the two sets of battery packs 31 are arranged in parallel on the left and right sides of the rear portion of the main body case 11. Compared with the separate arrangement of the two sets of battery packs 31, this facilitates the attachment and detachment of the battery packs 31 for the user.

[0029] Since the chain saw 10 mounts a set of battery packs 31 comprising two battery packs 31, the rear portion of the main body case 11 has two mounting portions 25 corresponding to the battery packs 31. The battery packs 31 each have, on the peripheral wall of the case 32 in which the battery cell 33 is housed, the electrical terminal 34 and the pair of rails 35 arranged on both sides of the electrical terminal 34, and the mounting portions 25 each have a terminal portion 25a for electrically connecting to the electrical terminal 34 of the battery packs 31 and the pair of guide rails 25b slidably engaged with the pair of rails 35.By sliding the pair of rails 35 of the battery packs 31 on the guide rails 25b of the attachment portion 25, that is, by slidingly displacing the battery packs 31 with respect to the attachment portion 25, the battery packs 31 can be attached to the attachment portions 25 in an electrically connected state, which improves the operability of attaching the battery packs 31 to the attachment portions 25.

[0030] In addition, the battery packs 31 each have the hook 36 projecting toward and retracting from the attachment portion 25, and the attachment portions 25 each have the engaging portion 25c into which the hook 36 engages. The hook 36 is biased by the spring member 37 to engage the engaging portion 25c. Since the hook 36 is biased by the spring member 37 to engage the engaging portion 25c, displacement of the battery packs 31 from the attachment portions 25 is restricted, so that the battery packs 31 do not detach from the attachment portions 25. If the hook 36 is released from the locking portion 25c against the pretensioning force of the spring element 37, the battery packs 31 can be moved from the attachment portions 25 so that the battery packs 31 can be removed from the attachment portions 25.Thus, merely by operating the hook 36, the battery packs 31 can be restricted from sliding on the attachment portions 25, or they can be brought into a sliding state, thereby improving the operability of attaching the battery packs 31 to the attachment portions 25.

[0031] Furthermore, the guide rails 25b on the attachment portions 25 are inclined approximately 10° from the vertical, and the battery packs 31 are attached to the rear portion of the main body case 11 at an angle of approximately 10° from the vertical on both sides of the attachment portions 25. By attaching the battery packs 31 in an angled manner backward, the operator can hold the side handle 15 of the chain saw 10 placed on the ground or the like with one hand and push it toward the ground, and grasp the battery pack 31 with the other hand and pull it up obliquely backward in the direction opposite to the side handle 15, thereby easily detaching the battery pack 31 from the attachment portion 25.

[0032] Next, modification examples of the chainsaw 10 using the set of battery packs 31 comprising two battery packs 31 will be described. In the following description, the differences from the chainsaw 10 of the above-described embodiment will be primarily described, and unless otherwise specified, the previously described functions will be omitted. Furthermore, since the guide bar 21, the saw chain 22, and the electric motor 23 are identical to the above-described embodiment in the individual figures of the modification examples, their illustration will be omitted. First variation example

[0033] In the electrically driven chain saw 10 of the above-described embodiment, the attachment portions 25 protrude, as shown in the rear view of Fig. 4, without inclination left and right outwardly, while in the chain saw 10 of the first modification example, the left and right attachment portions 25 are arranged with the top inclined outwardly on the left and right sides at the rear portion of the main body case 11, as shown in the rear view of Fig. 8, whereby the battery packs 31 are mounted with the tops inclined outward on the left and right sides to the rear portion of the main body case 11. Second variation example

[0034] In the electrically driven chain saw 10 of the embodiment described above, the battery packs 31 are arranged as shown in the right side view of Fig. 3 and the rear view of Fig. 4, the battery packs 31 are mounted on the left and right sides at the rear portion of the main body case 11 by sliding from above, while in the chain saw 10 of the second modification example, the battery packs 31 are mounted on the left and right sides at the rear portion of the main body case 11 by sliding from below by arranging the mounting portions 25 inversely as in the rear view in Fig. 9 shown. Third variation example

[0035] In the electrically driven chain saw 10 of the above-described embodiment, the attachment portions 25 are inclined by about 10° from the vertical, as shown in the right side view of Fig. 3, and the battery packs 31 are mounted on the rear portion of the main body case 11 inclined backward by about 10° from the vertical on both sides, while in the chain saw 10 of the third modification example, the mounting portions 25 project vertically upward and the battery packs 31 are mounted vertically upward on the left and right sides of the rear portion of the main body case 11, as shown in the right side view of Fig. 10. In this way, the operator can hold the rear handle 13 or the front handle 15 of the chainsaw 10 placed on the ground or the like with one hand and push it toward the ground, and with the other hand grasp and pull up the battery pack 31, thereby easily detaching the battery pack 31 from the attachment portion 25. Fourth variation example

[0036] In the electrically driven chain saw 10 of the above-described embodiment, the attachment portions 25 are inclined by about 10° from the vertical, as shown in the right side view of Fig. 3, and the battery packs 31 are mounted on the rear portion of the main body case 11 inclined backward by about 10° from the vertical on both sides, while in the chain saw 10 of the fourth modification example, the mounting portions 25 are inclined forward by about 10° from the vertical and the battery packs 31 are mounted inclined forward by about 10° from the vertical on the left and right sides on the rear portion of the main body case 11 as shown in the right side view of Fig. 11. In this way, the operator can hold the rear handle 13 of the chainsaw 10 placed on the ground or the like with one hand and push it toward the ground, and with the other hand grasp the battery pack 31 and pull it obliquely forward in the direction opposite to the rear handle 15, thereby easily detaching the battery pack 31 from the attachment portion 25. Fifth variation example

[0037] In the electrically driven chain saw 10 of the fifth modification example, as shown in the right side view of Fig. 12, on the surface of the rear portion of the main body case 11, two attachment portions 25 are arranged left and right in a row, and the two battery packs 31 of the set of battery packs 31 are attached to the surface of the rear portion of the main body case 11, arranged left and right in a row, to each of the attachment portions 25. The two attachment portions 25 and the two battery packs 31 are arranged on the left and right sides of the vertically extending center line C centered in the left-right direction of the grip portion 13a of the rear grip 13 (the rear view is omitted), and the center of gravity of the chain saw 10 when viewed from the rear is located in the range R that is 1.5 times the width of the grip portion 13a in the left-right direction from the center line C.The distance between adjacent wall surfaces of the battery packs 31 arranged in a row on the left and right is 5 mm, thereby reducing the space occupied by the two battery packs 31. As long as the distance between adjacent wall surfaces of the two battery packs 31 arranged in a row on the left and right of the set of battery packs 31 is less than 15 mm, the space occupied by the two battery packs 31 of the set of battery packs 31 can be sufficiently reduced.

[0038] Furthermore, the attachment portions 25 are inclined such that the rear portion is positioned at the top of the rear portion surface of the main body case 11, and the battery packs 31 are mounted at an inclination such that the rear portion is positioned at the top of the rear portion surface of the main body case 11. In this way, the operator can hold the side handle 15 of the chainsaw 10 placed on the ground or the like with one hand and push it toward the ground, and grasp the battery pack 31 with the other hand and pull it up obliquely backward in the direction opposite to the front handle 15, thereby easily detaching the battery pack 31 from the attachment portion 25. Sixth variation example

[0039] In the electrically driven chain saw 10 of the sixth modification example, as shown in the right side view of Fig. 13, in the chain saw 10 of the above-described embodiment, a battery pack receiving cover 16 is provided on the periphery of each of the attachment portions 25 of the main body casing 11, with the top thereof open. The battery pack receiving cover 16 covers all but the upper end portion of the battery pack 31. Since the battery pack receiving cover 16 covers most of the battery pack 31, it protects the battery pack 31 from damage during operation. In addition, a spring member 17 formed of a leaf spring is provided at the bottom portion of the battery pack receiving cover 16, and the battery pack 31 is biased upward by the spring member 17.When the battery pack 31 is attached to the attachment portion 25 inside the battery pack receiving cover 16, the hook 36 of the battery pack 31 is disengaged from the engaging portion 25c of the attachment portion 25, the battery pack 31 is pushed upward by the biasing force of the spring member 17. As a result, the upper portion of the battery pack 31 protrudes from the opening at the top of the battery pack receiving cover 16, so that the upper portion of the battery pack 31 can be grasped and easily pulled upward from the battery pack receiving cover 16. Seventh variation example

[0040] In the electrically driven chain saw 10 of the seventh modification example, as shown in the right side view of Fig. 14, a battery pack receiving portion 11c is provided inside the main body casing 11. The main body casing 11 is divided into a main body portion 11a without the rear portion and a rear portion 11b having the rear handle 13, with the upper end of the rear portion 11b being rotatably supported at the front about a horizontal axis at the rear of the upper end of the main body portion 11a. Two battery pack receiving portions 11c are provided on the main body portion 11a of the main body casing 11, and the battery pack receiving portions 11c are open at the rear when the rear portion 11b is rotated. The battery packs 31 are detachably attached to the upper and lower battery pack receiving portions 11c via the rear opening.The above-described attachment portions 25 are provided on the battery pack receiving portions 11c, and the battery packs 31 received in the respective battery pack receiving portion 11c are detachably attached to the attachment portions 25. The upper attachment portion 25 is provided in the lower portion of the battery pack receiving portion 11c, and the lower attachment portion 25 is provided in the upper portion of the battery pack receiving portion 11c, such that the upper and lower attachment portions 25 are positioned adjacent to each other.

[0041] Furthermore, a spring member 17 formed of a leaf spring is provided at a deep portion of the battery pack receiving portion 11c, and the battery pack 31 is biased rearward by the spring member 17. In the state where the battery pack 31 is attached to the attachment portion 25 inside the battery pack receiving portion 11c, when the rear portion 11b of the main body case 11 is rotated upward and the hook 36 of the battery pack 31 is released from the locking portion 25c of the attachment portion 25, the battery pack 31 is pushed rearward by the biasing force of the spring member 17. As a result, the rear portion of the battery pack 31 protrudes from the opening at the rear of the battery pack receiving portion 11c, so that the rear portion of the battery pack 31 can be grasped and easily pulled rearward from the battery pack receiving portion 11c. Eighth variation example

[0042] In the electrically driven chain saw 10 of the eighth modification example, as shown in the right side view of Fig. 15, a battery pack receiving portion 11c is provided inside the main body casing 11. The main body casing 11 is divided into a main body portion 11a without the rear portion and a rear portion 11b having the rear handle 13, wherein the upper end of the rear portion 11b is rotatably supported at the front about a horizontal axis at the rear of the upper end of the main body portion 11a. Two battery pack receiving portions 11c are provided on the main body portion 11a of the main body casing 11 (in Fig. 15, only the right battery pack receiving portion 11c is shown, while the left battery pack receiving portion 11c, which is mirror-symmetrical to the right attachment portion, is omitted. The battery pack receiving portions 11c are open at the rear in a rotated state of the rear portion 11b. The battery packs 31 are detachably attached to the left and right battery pack receiving portions 11c via the rear opening. The above-described attachment portions 25 are provided on the battery pack receiving portions 11c, and the battery packs 31 received in the respective battery pack receiving portion 11c are detachably attached to the attachment portions 25.The left attachment portion 25 is provided in the right portion of the battery pack receiving portion 11c, and the right attachment portion 25 is provided in the left portion of the battery pack receiving portion 11c, such that the left and right attachment portions 25 are positioned adjacent to each other in the left-right direction central portion of the main body case 11.

[0043] Furthermore, as in the seventh modification example, a spring member 17 formed of a leaf spring is provided at a deep portion of the battery pack receiving portions 11c, and the battery pack 31 is biased rearward by the spring member 17. In the state where the battery pack 31 is attached to the attachment portion 25 inside the battery pack receiving portion 11c, when the rear portion 11b of the main body case 11 is rotated upward and the hook 36 of the battery pack 31 is released from the locking portion 25c of the attachment portion 25, the battery pack 31 is pushed rearward by the biasing force of the spring member 17. As a result, the rear portion of the battery pack 31 protrudes from the opening at the rear of the battery pack receiving portion 11c, so that the rear portion of the battery pack 31 can be grasped and easily pulled out of the battery pack receiving portion 11c to the rear. Ninth variation example

[0044] In the electrically driven chain saw 10 of the ninth modification example, as shown in the right side view of Fig. 16, upper and lower battery pack receiving portions 11c are provided at the rear portion of the main body case 11. The right side surfaces of the battery pack receiving portions 11c are open, and the battery packs 31 are received in the battery pack receiving portions 11c through this opening. The above-described attachment portions 25 are provided at the battery pack receiving portions 11c, and the battery packs 31 received in the respective battery pack receiving portion 11c are detachably attached to the attachment portions 25. The upper attachment portion 25 is provided in the lower portion of the battery pack receiving portion 11c, and the lower attachment portion 25 is provided in the upper portion of the battery pack receiving portion 11c such that the upper and lower attachment portions 25 are positioned adjacent to each other.

[0045] Furthermore, at a deep portion constituting a left side portion of the battery pack receiving portions 11c, the spring member (not shown) formed of a leaf spring shown in the seventh modification example is provided, and the battery packs 31 are biased rightward by the spring member. In the state where a battery pack 31 is attached to the attachment portion 25 inside a battery pack receiving portion 11c, when the hook 36 of the battery pack 31 is released from the locking portion 25c of the attachment portion 25, the battery pack 31 is pushed rightward by the biasing force of the spring member. As a result, the right portion of the battery pack 31 protrudes from the opening on the right side of the battery pack receiving portion 11c, so that the rear portion of the battery pack 31 can be grasped and easily pulled out of the battery pack receiving portion 11c to the right. Tenth variation example

[0046] In the electrically driven chain saw 10 of the tenth modification example, as shown in Fig. 17, front and rear battery pack receiving portions 11c are provided at the rear bottom of the main body case 11. The right side surface of the battery pack receiving portions 11c is open, and the battery packs 31 are received in the battery pack receiving portions 11c through this opening. The distance between adjacent wall surfaces of the battery packs 31 mounted in a row at the front and rear is 5 mm, thereby reducing the space occupied by the two battery packs 31. As long as the distance between adjacent wall surfaces of the two battery packs 31 mounted in a row on the left and right is less than 15 mm, the space occupied by the two battery packs 31 can be sufficiently reduced.The above-described attachment portions 25 are provided at the top of the battery pack receiving portions 11c, and the battery packs 31 received in the respective battery pack receiving portion 11c are detachably attached to the attachment portions 25.

[0047] In addition, at a deep portion constituting a left side portion of the battery pack receiving portions 11c, the leaf spring member (not shown) shown in the seventh and eighth modifications is provided, and the battery packs 31 are biased rightward by the spring member. In the state where a battery pack 31 is mounted inside a battery pack receiving portion 11c on the mounting portion 25, when the hook 36 of the battery pack 31 is disengaged from the engaging portion 25c of the mounting portion 25, the battery pack 31 is pushed rightward by the biasing force of the spring member. As a result, the right portion of the battery pack 31 protrudes from the opening on the right side of the battery pack receiving portion 11c, so that the rear portion of the battery pack 31 can be grasped and easily pulled out of the battery pack receiving portion 11c to the right. Eleventh variation example

[0048] In the electrically driven chain saw 10 of the eleventh modification example, as shown in Fig. 18, two mounting portions 25 are arranged in a row at the front and rear of the rear portion of the main body case 11 under the rear handle 13, and the two battery packs 31 are mounted on the rear portion of the main body case 11, arranged in a row at the front and rear, respectively, under the rear handle 13. The distance between adjacent wall surfaces of the battery packs 31 mounted in a row at the front and rear is 5 mm, thereby reducing the space occupied by the two battery packs 31. As long as the distance between adjacent wall surfaces of the two battery packs 31 mounted in a row on the left and right is less than 15 mm, the space occupied by the two battery packs 31 can be sufficiently reduced.The centers of gravity of the two battery packs 31 are located on the left and right sides of the vertically extending center line C centered in the left-right direction in the area R of the rear handle portion 1.5 times the width W (30 mm) when viewed from the rear, and the center of gravity of the chainsaw 10 is located on the left and right sides of the vertically extending center line C centered in the left-right direction when viewed from the rear. In the above embodiment, the distance between adjacent wall surfaces of the two battery packs 31 of the set of battery packs 31 is 5 mm, but when the distance between adjacent wall surfaces of the two battery packs 31 is 15 mm or more, a finger can be inserted between the two battery packs 31, which facilitates attachment and detachment. Twelfth variation example

[0049] In the electrically driven chain saw 10 of the twelfth modification example, as shown in Fig. 19, at the rear portion of the main body casing 11 under the rear handle 13, two attachment portions 25 are arranged left and right in a row, and the two battery packs 31 are attached to the rear portion of the main body casing 11, respectively, arranged left and right in a row under the rear handle 13 (in Fig. 19, only the right mounting portion 25 and the right battery pack 31 are shown, while the left mounting portion 25 and the left battery pack 31, which are mirror-symmetrical to the right side, are omitted. The distance between adjacent wall surfaces of the battery packs 31 mounted on the left and right in a row is 5 mm, thereby reducing the space occupied by the two battery packs 31. As long as the distance between adjacent wall surfaces of the two battery packs 31 mounted on the left and right in a row is less than 15 mm, the space occupied by the two battery packs 31 can be sufficiently reduced.The centers of gravity of the two battery packs 31 are located on the left and right sides of the vertically extending center line C centered in the left-right direction of the grip portion 13a of the rear grip 13 in the area R that is 1.5 times the width W (30 mm) of the grip portion of the rear grip when viewed from the rear, and the center of gravity of the chainsaw 10, when viewed from the rear, is located on the left and right sides of the left-right direction of the vertically extending center line C centered in the left-right direction of the grip portion 13a of the rear grip 13 in the area R that is 1.5 times the left-right length of the grip portion 13a. In addition, the centers of gravity G1 of the two battery packs 31 are distributed on both sides of the vertically extending center line C of the grip portion 13a.In the above embodiment, the distance from adjacent wall surfaces of the two battery packs 31 is 5 mm, but when the distance from adjacent wall surfaces of the two battery packs 31 is 15 mm or more, a finger can be inserted between the two battery packs 31, which facilitates attachment and detachment. Thirteenth variation example

[0050] In the electrically driven chain saw 10 of the thirteenth modification example, as shown in Fig. 20, two attachment portions 25 are arranged at the rear portion of the main body casing 11 in the middle portion in the left-right direction under the rear handle 13, and the two battery packs 31 are attached to the rear portion of the main body casing 11 on the left and right respectively under the rear handle 13 (in Fig.20, only the right attachment portion 25 and the right battery pack 31 are shown, while the left attachment portion 25 and the left battery pack 31, which are mirror-symmetrical to the right side, are omitted. The centers of gravity G of the two battery packs 31 are located on the left and right sides of the vertically extending center line C in the area R that is 1.5 times the width W (30 mm) of the grip portion 13a of the rear grip 13 when viewed from the rear, and the center of gravity of the chain saw 10, when viewed from the rear, is located on the left and right sides of the vertically extending center line C in the area R that is 1.5 times the width W (30 mm) of the grip portion 13a of the rear grip 13. In addition, the centers of gravity G1 of the two battery packs 31 are arranged distributed on the two sides of the center line C extending in the vertical direction of the handle portion 13a.

[0051] In the chain saw 10 constructed as described above, it has been described that the battery packs 31 are connected in series with the electric motor 23, but the present invention is not limited to this. When the two battery packs 31 of the set of battery packs 31 are connected in series with the electrically driven motor 23, the electric motor 23 can be used with high output power, and when the two battery packs 31 of the set of battery packs 31 are connected in parallel with the electric motor 23, the electric motor 23 can be used for a long time. It is also possible to select between series connection and parallel connection by a control circuit. Explanation of reference symbols

[0052] 10: Chainsaw, 11: Main body, 21: Guide bar, 22: Saw chain, 23: Electric motor, 25: Attachment section, 25a: Connection section, 25b: Guide bar, 25c: Locking section, 30: Power source, 31: Battery pack, 32: Housing, 33: Battery cell, 34: Electrical connector, 35: Bar, 36: Hook, G: Center of gravity of the chainsaw, G1: Center of gravity of the battery pack, C: Center line (center line extending vertically in the left-right direction as viewed from the rear side of the handle section), R: Area (area 1.5 times the length of the handle section in the left-right direction, on the left and right sides of the center line C of the handle section)

Claims

[1] Electrically powered chainsaw (10), comprising a main body housing (11) accommodating an electric motor (23) powered by a rechargeable battery, a guide rod (21) which is fixed at its base end to a side portion of the main body casing (11) and projects forward, a saw chain (22) which is stretched around the outer circumference of the guide rod (21) and is driven by the electric motor (23), a rear handle (13) extending rearwardly from a rear portion of the main body housing (11) and held by the operator, and an arcuate front handle fixed at its left and right lower end portions to both sides of the main body casing (11), wherein the electric motor (23) is started by an operating switch on the rear handle (13), wherein a set of compact, general-purpose battery packs (31) which are also usable for electrically powered working devices such as electrically powered tools, electrically powered gardening equipment or the like is used as the rechargeable battery, wherein the main body casing (11) comprises on the left and right sides at the rear portion of the main body casing (11) an attachment portion (25) for each battery pack (31) of the set of battery packs (31) to be attached, wherein the attachment portion (25) comprises a pair of guide rails (25b) extending in the vertical direction, wherein the battery packs (31) of the set of battery packs (31) are configured to be vertically slidable along the guide rails (25b), and wherein the set of general-purpose battery packs (31) is attached to the rear portion of the main body casing (11) such that a center of gravity (G) of the chain saw (10), when the battery packs (31) of the set of battery packs (31) are attached to the attachment portions (25), is located in an area (R) that is 1.5 times a width (W) (30 mm) of a grip portion (13a) of the rear grip (13), on the left and right sides of a vertically extending center line (C) centered in the left-right direction, and wherein left and right attachment portions (25) for the battery packs (31) are arranged mirror-symmetrically to the center line (C). [2] The electric-powered chain saw (10) according to claim 1, wherein the centers of gravity (G1) of the battery packs (31) of the set of battery packs (31) are arranged in a range (R) which is 1.5 times the width (W) of the grip portion (13a) of the rear grip (13) on the left and right sides of the vertically extending center line (C) centered in the left-right direction. [3] An electrically powered chain saw (10) according to claim 1, wherein the centers of gravity (G1) of the battery packs (31) of the set of battery packs (31) are located on the left and right sides of the vertically extending center line (C) centered in the left-right direction of the handle portion (13a). [4] An electrically powered chain saw according to claim 1, wherein the battery packs (31) of the set of battery packs (31) are mounted on the main body case (11) in a parallel arrangement. [5] An electrically powered chain saw (10) according to claim 1, wherein the battery packs (31) of the set of battery packs (31) are detachably attached to the main body case (11) in a direction orthogonal to the longitudinal direction of the main body case (11) arranged in parallel. [6] An electrically powered chain saw (10) according to claim 1, wherein the battery packs (31) of the set of battery packs (31) are detachably mounted on the main body case (11) in a horizontally parallel arrangement. [7] An electrically powered chain saw (10) according to claim 1, wherein the battery packs (31) of the set of battery packs (31) are connected in series with the electric motor (23). [8] An electrically powered chain saw (10) according to claim 1, wherein the battery packs (31) of the set of battery packs (31) are connected in parallel with the electric motor (23).

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