Patent Description:
A work tool including a power source such as an electric motor or an internal combustion engine is linked to a worker by using a lifting hook and a carabiner during work or interruption of work. <CIT> discloses an example in which a worker wears a harness including a hip pad to use a combination of a lifting hook and a carabiner for linking the harness to a bush cutter. <CIT> discloses an example in which a combination of a lifting hook and a carabiner is used to suspend a rechargeable electric work tool from a waist belt of a worker when the tool is not in use.

Several typical examples of conventional lifting hooks manufactured by bending one rod will be described with reference to <CIT>, <CIT>, and <CIT>.

<CIT> proposes a lifting hook locking a hand-held work tool such as an electric screwdriver or an electric or gas-combustion tacker to a waist belt. This lifting hook is for directly locking to the waist belt.

<CIT> and <CIT> propose lifting hooks locking a work tool to a waist belt via a carabiner or a rope attached to the waist belt, and these hooks have a flat U-shape, are both pivotally assembled to the work tool, and can take a use position projected from the work tool and a retracted position housed in a recess of the work tool.

The lifting hook of <CIT> is located on a vertical plane when the hook is attached to a work tool. The lifting hook of <CIT> is located on a horizontal plane when the hook is attached to a work tool. As used herein, the term "vertical" means, for example, a body height direction, i.e., an up-down direction, when a worker with the carabiner disposed on a waist belt takes a standing posture and holds the work tool in a natural posture. The term "horizontal" means a lateral direction orthogonal to the body height direction. As used herein, the term "natural posture" means a state in which the worker holds the work tool without twisting the wrist.

To distinguish the lifting hooks disclosed in <CIT> and <CIT>, the lifting hook of <CIT> is referred to as a "vertical hook", and the lifting hook of <CIT> is referred to as a "horizontal hook".

Available carabiners can roughly be classified into two types. A first type is a "lever type carabiner" including a gate lever. A second type is a "safety lock type carabiner" including a locking mechanism using a screw. The lever type carabiner is employed to link a hand-held work tool to the body of a worker.

The lever type carabiners can roughly be classified into two types depending on a length of a nose defining a gate portion of a carabiner body. Typical examples of carabiners employed for locking a hand-held work tool are shown in <FIG> and <FIG>. A carabiner <NUM> of <FIG> is a "short-nose carabiner". A carabiner <NUM> of <FIG> is a "long-nose carabiner".

Referring to <FIG>, the short-nose carabiner <NUM> has a carabiner body <NUM>, a gate lever <NUM> disposed in a gate portion <NUM> of the carabiner body <NUM>, and a nose part <NUM> with which a free end of the gate lever <NUM> is engaged. The gate lever <NUM> has a structure providing a spring function, and this spring function constantly urges the gate lever <NUM> in the closing direction. The long-nose carabiner <NUM> (<FIG>) includes substantially the same constituent elements and additionally has a spring member (not shown) urging the gate lever <NUM>. This spring member constantly urges the gate lever <NUM> of the long-nose carabiner <NUM> in the closing direction. The short-nose carabiner <NUM> and the long-nose carabiner <NUM> have a base end 14a of the gate lever <NUM> pivotally supported by the carabiner body <NUM>.

As can be seen by comparing <FIG> and <FIG>, the nose part <NUM> of the short-nose carabiner <NUM> has a shorter distance L(s) from a locking point 16a for locking the free end of the gate lever <NUM> to a tip 16b. On the other hand, the long-nose carabiner <NUM> has a longer distance L(L) from the locking point 16a to the tip 16b, and the nose part <NUM> from the locking point 16a to the tip 16b, i.e., a nose extension part <NUM> is curved outward (<FIG>).

To attach a lifting hook of a work tool to the lever type carabiner and to remove the hook from the carabiner, a worker is required to perform an operation of pushing down and opening the gate lever <NUM> against the spring force. Operations of the worker holding the work tool employing the vertical hook (<CIT>) or the horizontal hook (<CIT>) will hereinafter be described with reference to <FIG>.

<FIG> and <FIG> are views for explaining an operation at the time of attaching a vertical hook <NUM> to the short-nose carabiner <NUM>. In the figures, "Wk" denotes a worker. "Wb" denotes a waist belt. The vertical hook <NUM> is disposed on a rear end surface of a work tool TL. The work tool TL shown in the figures is illustrated as a rechargeable electric chainsaw. This chainsaw TL is a top handle type.

<FIG> shows a preparation step for attaching the vertical hook <NUM> to the short-nose carabiner <NUM>. The worker Wk lifts the chainsaw TL and rotates an arm Am and/or a wrist Wr, i.e., twists the arm Am and/or the wrist Wr, to position an upper leg 20u of the vertical hook <NUM> on the free end of the gate lever <NUM> and position a lower leg 20d outside the nose part <NUM>.

<FIG> shows a step of pushing down the gate lever <NUM> against the spring force with the upper leg 20u of the vertical hook <NUM> and inserting the upper leg 20u into the carabiner body <NUM>. This step can be performed by the worker Wk rotating and pushing down the chainsaw TL. As a result, the gate lever <NUM> is opened against the spring force, and the upper leg 20u can be inserted into the carabiner body <NUM>. The gate lever <NUM> is then automatically closed by the spring force. By the operation described above, the vertical hook <NUM> is completely attached to the short-nose carabiner <NUM>, and the chainsaw TL is engaged with the carabiner <NUM> via the vertical hook <NUM>. Consequently, the chainsaw TL is suspended from the waist of the worker Wk via the carabiner <NUM>.

<FIG> and <FIG> are views for explaining an operation of detaching the vertical hook <NUM> locked to the short-nose carabiner <NUM> from the carabiner <NUM>. <FIG> shows a detachment preparation step. The worker Wk moves the arm Am upward to lift the chainsaw TL and then performs an operation of bringing the chainsaw TL closer to the body side of the worker Wk. As a result, the lower leg 20d of the vertical hook <NUM> can be located on a free end portion of the gate lever <NUM>.

<FIG> is a view for explaining an operation of pushing down the lower leg 20d located on the free end portion of the gate lever <NUM> and inserting the lower leg 20d into the carabiner body <NUM>. This operation is performed by the worker Wk lowering the arm Am and pushing down the chainsaw TL. As a result, both the upper leg 20u and the lower leg 20d can be inserted into the carabiner body <NUM>. Subsequently, by moving the arm Am forward or downward from this state, the vertical hook <NUM> located inside the carabiner body <NUM> can be pulled out. By the operation described above, the vertical hook <NUM> is completely detached from the short-nose carabiner <NUM>, and the chainsaw TL is released from the carabiner <NUM>.

<FIG> and <FIG> are views for explaining an operation at the time of attaching a horizontal hook <NUM> to the short-nose carabiner <NUM>. <FIG> shows a preparation step for attaching the horizontal hook <NUM> to the short-nose carabiner <NUM>. The worker Wk lifts the chainsaw TL and rotates the arm Am or twists the wrist Wr to face the rear end surface of the chainsaw TL toward the body side. A connecting part 30cn connecting ends of an inner leg 30in and an outer leg 30out of the horizontal hook <NUM> is positioned on the free end portion of the gate lever <NUM>.

<FIG> shows a step of inserting the connecting part 30cn of the horizontal hook <NUM> into the carabiner body <NUM>. This inserting step can be performed by pushing down the chainsaw TL. This causes the connecting part 30cn to open the gate lever <NUM> against the spring force, and the connecting part 30cn is inserted into the carabiner body <NUM>. As a result, the horizontal hook <NUM> is completely attached to the short-nose carabiner <NUM>, and the chainsaw TL is engaged with the carabiner <NUM> via the horizontal hook <NUM>.

<FIG> and <FIG> are views for explaining an operation of detaching the horizontal hook <NUM> attached to the short-nose carabiner <NUM> from the carabiner <NUM>. <FIG> shows a detachment preparation step. The worker Wk lifts and rotates the arm Am to position the outer leg 30out of the horizontal hook <NUM> on the gate lever <NUM>. <FIG> shows a step of inserting the outer leg 30out of the horizontal hook <NUM> into the carabiner body <NUM>. This step can be performed by pushing down the chainsaw TL with the arm Am. As a result, both the inner leg 30in and the outer leg 30out can be inserted into the carabiner body <NUM>. Subsequently, by moving the arm Am forward from this state, the horizontal hook <NUM> located inside the carabiner body <NUM> can be pulled out. As a result of the operation, the horizontal hook <NUM> is completely detached from the short-nose carabiner <NUM>, and the chainsaw TL is released from the carabiner <NUM>.

<FIG> and <FIG> are views for explaining an operation at the time of attaching the vertical hook <NUM> to the long-nose carabiner <NUM>. <FIG> shows an attachment preparation step. The worker Wk lifts the rear end surface of the chainsaw TL and twists the arm Am and/or the wrist Wr to position the lower leg 20d of the vertical hook <NUM> on the free end of the gate lever <NUM> and position the upper leg 20u outside the nose extension part <NUM>.

<FIG> shows a step of pushing down the gate lever <NUM> with the lower leg 20d of the vertical hook <NUM> to insert the lower leg 20d into the carabiner body <NUM>. This step can be performed by the worker Wk pushing down the chainsaw TL. By this operation, the vertical hook <NUM> is completely attached to the long-nose carabiner <NUM>, and the chainsaw TL is engaged with the carabiner <NUM> via the vertical hook <NUM>.

<FIG> are views for explaining an operation of detaching the vertical hook <NUM> locked to the long-nose carabiner <NUM> from the carabiner <NUM>. <FIG> shows a detachment preparation step. Referring to <FIG>, first, the worker Wk lifts the chainsaw TL to raise the upper leg 20u of the vertical hook <NUM> along the nose extension portion <NUM> so that the upper leg 20u then climbs over the nose extension portion <NUM>. <FIG> and <FIG> show a step of inserting the upper leg 20u into the carabiner body <NUM>. This step is performed by pushing down the free end portion of the gate lever <NUM> with the upper leg 20u. Specifically, the worker Wk pushes down the chainsaw TL to open the gate lever <NUM> against the spring force with the upper leg 20u, and the upper leg 20u can then be inserted into the carabiner body <NUM> (<FIG>). Subsequently, by moving the arm Am forward, the vertical hook <NUM> located inside the carabiner body <NUM> can be pulled out. By the operation described above, the vertical hook <NUM> is completely detached from the long-nose carabiner <NUM>, and the chainsaw TL is released from the carabiner <NUM>.

<FIG> and <FIG> are views for explaining an operation at the time of attaching the horizontal hook <NUM> to the long-nose carabiner <NUM>. <FIG> shows an attachment preparation step. The worker Wk lifts and brings the chainsaw TL closer to the body side so that the horizontal hook <NUM> climes over the nose extension part <NUM> (<FIG>). The chainsaw TL is then pushed down to open the gate lever <NUM> against the spring force (<FIG>), and the horizontal hook <NUM> is inserted into the carabiner body <NUM>. When this is finished, the gate lever <NUM> automatically returns to the closed state due to the spring force. By this series of operations, the horizontal hook <NUM> is completely attached to the long-nose carabiner <NUM>, and the chainsaw TL is engaged with the long-nose carabiner <NUM> via the horizontal hook <NUM>.

<FIG> is a view for explaining an operation of detaching the horizontal hook <NUM> locked to the long-nose carabiner <NUM> from the carabiner <NUM>. The worker Wk lifts the chainsaw TL to raise the outer leg 30out of the horizontal hook <NUM> along the nose extension part <NUM> and moves the outer leg 30out by rotating the wrist Wr upward and sideways, i.e., by a twisting motion of the wrist Wr, to climb over the nose extension part <NUM>. The outer leg 30out is positioned on the free end of the gate lever <NUM> and is then pushed down. Specifically, the worker Wk pushes down the chainsaw TL to open the gate lever <NUM> with the outer leg 30out and inserts the outer leg 30out into the carabiner body <NUM>. Subsequently, by moving the arm Am forward, the horizontal hook <NUM> located in the carabiner body <NUM> can be pulled out. By the operation described above, the horizontal hook <NUM> is completely detached from the long-nose carabiner <NUM>, and the chainsaw TL is released from the carabiner <NUM>.

As described above, to lock/detach the conventional vertical or horizontal hook <NUM>, <NUM> to/from the short-nose or long-nose carabiner <NUM>, <NUM>, the worker Wk needs to perform an up-down motion and a rotating motion of the arm (arm twisting motion) and an up-down motion or left/right rotating motion of the wrist Wr (wrist twisting motion). Explaining an example of a situation where the chainsaw illustrated as the work tool TL is locked to the carabiner <NUM>, <NUM>, when pruning and trimming a tree, a worker Wk climbs the tree by using a rope etc. and performs a work while moving on the tree. When the chainsaw is not used, the worker Wk moves, or performs another work, while the chainsaw is locked to the carabiner <NUM>, <NUM> on a waist belt Wb. In such an unstable state, it is required to simplify the motions of the arm Am, a hand Hd, and the wrist Wr related to the operation of the worker Wk locking/detaching the hook <NUM>, <NUM> to/from the carabiner <NUM>, <NUM> as much as possible.

An object of the present invention is to provide a lifting hook capable of simplifying a worker's motion for locking to/ detaching from a carabiner attached to the worker's body to reduce a burden of the worker.

According to one aspect of the present invention, the technical problem described above is solved by providing a system comprising a lifting hook and a work tool with a power source according to independent claim <NUM>.

Effects and other objects of the present invention will become apparent from the following detailed description of preferable examples of the present invention.

Preferable embodiments of the present invention will now be described with reference to the accompanying drawings. Prior to the description, an overview of one embodiment will be described with reference to <FIG>. In the following description, for example, based on a carabiner attached to the worker's body via a waist belt or a harness, a direction toward the carabiner (the worker's body) is indicated by "IN"; a direction away from the carabiner (the worker's body) is indicated by "OUT"; and an upward direction and a downward direction of the up-down directions of the carabiner (body height directions of the worker) are indicated by "UP" or "upward" and "DOWN" or "downward", respectively.

The inventors of the present application studied and analyzed conventional vertical and horizontal hooks <NUM> and <NUM> in terms of motions of a worker locking/detaching the hooks <NUM>, <NUM> to/from a carabiner. In the following description, a plane extending in the body height direction of the worker holding a work tool, i.e., the up-down direction, is referred to as a "vertical plane", and a plane orthogonal to the vertical plane is referred to as a "horizontal plane". The conventional vertical hook <NUM> assembled to a work tool is arranged in the vertical plane. On the other hand, the conventional horizontal hook <NUM> is arranged in the horizontal plane. The present inventors got an idea assembling a lifting hook to a work tool so as to locate the lifting hook in an inclined plane inclined relative to the horizontal plane and thereby providing a height difference between an inner leg on the side close to the carabiner and an outer leg on the far side so that the outer leg is located at a relatively high position. Based on a hypothesis that this can be expected to reduce a worker's motion, especially, a twist of the wrist, at the time of locking/detaching a hook to/from a carabiner, a U-shaped lifting hook <NUM> was actually disposed in an inclined plane to verify the worker's motion.

<FIG> show the U-shaped lifting hook <NUM>. The hook <NUM> of the embodiment has an inner leg <NUM>, an outer leg <NUM>, and a connecting part <NUM> connecting free ends of the inner leg <NUM> and the outer leg <NUM>. The lifting hook <NUM> is assembled to a work tool and located in the inclined plane described above. In the lifting hook <NUM> located in the inclined plane, the inner leg <NUM> is located on the side close to the worker (carabiner), and the outer leg <NUM> is located on the side far from the carabiner. The outer leg <NUM> is located at a higher position than the inner leg <NUM>. Reference numeral "H" denotes a height difference between the inner leg <NUM> and the outer leg <NUM>. <FIG> is a cross-sectional view of the lifting hook <NUM>. Reference numeral "D" denotes a separation distance between the inner leg <NUM> and the outer leg <NUM> when the hook <NUM> is viewed from above.

Referring to <FIG>, a base end portion of the inner leg <NUM> is made up of an end 102a bent toward a body side, while a base end portion of the outer leg <NUM> is made up of an end 104a bent outward. The two bent ends 102a, 104a are inserted into a pair of attachment holes <NUM> of a work tool TL.

<FIG> and <FIG> are views for explaining an operation related to locking/detaching of the lifting hook <NUM> to/from a short-nose carabiner <NUM>. <FIG> is a view for explaining an operation when the lifting hook <NUM> is attached to the carabiner <NUM>. As indicated by an arrow, the worker moves the work tool TL in the direction toward the carabiner <NUM>, i.e., the worker's body, to bring the inner leg <NUM> into contact with a gate lever <NUM> constantly urged in a closing direction and then pushes down the hook <NUM> to put the inner leg <NUM> into the carabiner <NUM> while opening the gate lever <NUM> against the spring force with the inner leg <NUM>. As a result, the worker can attach the hook <NUM> to the short-nose carabiner <NUM> by moving the lifting hook <NUM> in the up-down and left-right directions via the work tool TL.

<FIG> is a view for explaining an operation when the lifting hook <NUM> is detached from the short-nose carabiner <NUM>. The worker moves the work tool TL in the direction toward the body to bring the outer leg <NUM> into contact with the gate lever <NUM>. The worker can then move the hook <NUM> downward via the work tool TL to open the gate lever <NUM> with the outer leg <NUM> against the spring force and put outer leg <NUM> into the carabiner body <NUM>. By moving the work tool TL forward from this state, the lifting hook <NUM> located inside the carabiner body <NUM> can be pulled out. By the operation described above, the lifting <NUM> is completely detached from the short-nose carabiner <NUM>, and the work tool TL can be released from the carabiner <NUM>.

The lifting hook <NUM> can be attached to and detached from the carabiner <NUM> by the operation related to the short-nose carabiner <NUM>, i.e., by simply moving the work tool TL in the up-down and left-right directions. In other words, the worker first visually or gropingly confirms the short-nose carabiner <NUM> and then attaches and detaches the lifting hook <NUM> without a motion such as "excessively" twisting an arm Am or a wrist Wr. As used herein, the term "excessively" means a twist of the arm Am or the wrist Wr at about <NUM>° or less, which is not a burden to the worker. Preferably, this means that the arm Am and the wrist Wr are "moderately" twisted to attach and detach the lifting hook <NUM>. As used herein, the term "moderately" means a twist of the arm Am or the wrist Wr at about <NUM>° or less, which is an optimum motion for the worker. Preferably, the lifting hook <NUM> can be attached to and detached from the short-nose carabiner <NUM> without twisting the arm Am or the wrist Wr at all.

<FIG> and <FIG> are views for explaining the operation when the lifting hook <NUM> is applied to a long-nose carabiner <NUM>. <FIG> is a view for explaining an operation when the lifting hook <NUM> is attached to the carabiner <NUM>. The worker lifts and moves the work tool TL in a lateral direction (toward the body side) to position the inner leg <NUM> over a nose extension part <NUM> and above the gate lever <NUM>. Subsequently, by pushing down the work tool TL, the gate lever <NUM> is opened against the spring force with the inner leg <NUM>, and the inner leg <NUM> is put into the carabiner body <NUM>. By the operation described above, i.e., by simply moving the work tool TL in the up-down direction and the direction toward the body side, the lifting hook <NUM> can be attached to the long-nose carabiner <NUM>. In other words, the worker can attach the hook <NUM> to the carabiner <NUM> while visually observing the operation, or in a groping manner, without a motion such as excessively twisting the arm Am or the wrist Wr. Preferably, the lifting hook <NUM> can be attached by moderately twisting the arm Am or the wrist Wr. Preferably, the lifting hook <NUM> can be attached without a motion such as twisting the arm Am or the wrist Wr at all.

<FIG> is a view for explaining an operation when the lifting hook <NUM> is detached from the long-nose carabiner <NUM>. The worker moves the work tool TL in a direction toward the body to position the outer leg <NUM> over the nose extension part <NUM> and above the gate lever <NUM>. In this state, since the outer leg <NUM> is located relatively higher than the inner leg <NUM>, the outer leg <NUM> can be positioned over the nose extension portion <NUM> and above the gate lever <NUM> by simply performing an operation of bringing the work tool TL closer to the body side of the worker. Subsequently, by moving the work tool TL downward, the gate lever <NUM> is opened against the spring force with the outer leg <NUM>, and the outer leg <NUM> is put into the carabiner body <NUM>. By moving the work tool TL forward from this state, the hook <NUM> located inside the carabiner body <NUM> can be pulled out. The operation described above is performed under visual observation or in a groping manner. The lifting hook <NUM> is completely detached from the long-nose carabiner <NUM> without an operation of rotating the work tool TL, i.e., without an operation of excessively twisting the arm Am or the wrist Wr, and the work tool TL can be released from the carabiner <NUM>. Preferably, the lifting hook <NUM> can be released by moderately twisting the arm Am or the wrist Wr. Preferably, the lifting hook <NUM> can be released without a motion such as twisting the arm Am or the wrist Wr at all.

Regarding the long-nose carabiner <NUM>, as with the short-nose carabiner <NUM>, the worker can attach and detach the lifting hook <NUM> to and from the long-nose carabiner <NUM> while visually observing the operation, or in a groping manner, without an operation such as twisting the arm Am or the wrist Wr.

In <FIG>, the connecting part <NUM> is inclined in the height direction to locate the outer leg <NUM> higher than the inner leg <NUM>. As in an example described below with reference to <FIG>, the outer leg <NUM> may be divided into two sections in the longitudinal direction thereof, and a first portion 104sub adjacent to the connecting part <NUM> may be inclined, so that a functional main portion 104main is located higher than the inner leg <NUM>. In a modification not shown, a portion adjacent to the connecting part <NUM> may be inclined in the inner leg <NUM>, so that the outer leg <NUM> is located higher than the inner leg <NUM>.

The inner leg <NUM>, the outer leg <NUM>, and the connecting part <NUM> shown as straight lines in <FIG> may have a curved shape. Alternatively, the inner leg <NUM>, the outer leg <NUM>, and the connecting part <NUM> may each have a shape acquired by combining a straight line and a curve.

<FIG> are views for explaining an action of the lifting hook <NUM> of an exemplary embodiment according to the present invention in comparison with a conventional example. <FIG> illustratively show the action of the conventional horizontal hook <NUM>, <FIG> is a view when the hook <NUM> is locked to the carabiner <NUM>(<NUM>), and <FIG> is a view when the hook <NUM> is detached from the carabiner <NUM>(<NUM>). <FIG> show the action of the lifting hook <NUM> of the embodiment, <FIG> is a view when the hook <NUM> is locked to the carabiner <NUM>(<NUM>), and <FIG> is a view when the hook <NUM> is detached from the carabiner <NUM>(<NUM>).

Referring to <FIG>, when the horizontal hook <NUM> located in the horizontal plane is detached from the short-nose and/or long-nose carabiner <NUM>(<NUM>), the work tool may be displaced in a lateral direction to open the lever <NUM> with the outer leg 30out. In this case, it is necessary to twist the wrist for the horizontal hook <NUM> depending on the size of the carabiner <NUM>(<NUM>). It may also be necessary to twist the wrist to incline the horizontal hook <NUM> upward or downward so as to put the outer leg 30out inside the body <NUM>. This inclination angle is indicated by γ1 and γ2 (<FIG>). The inclination angles γ1, γ2 vary depending on the size of the horizontal hook <NUM> and the size of the carabiner <NUM>, <NUM>.

With reference to <FIG>, the hook <NUM> of the embodiment has a height difference H between the inner leg <NUM> and the outer leg <NUM> and is therefore designed to reduce the twist, or preferably, to eliminate the need for the twist. For example, when the conventional horizontal hook <NUM> is detached from the carabiner <NUM>(<NUM>), it is necessary to twist the wrist to lift the outer leg 30out (<FIG>); however, this is not necessary for both locking and detaching the hook <NUM> of the embodiment (<FIG>). Although it may be necessary to twist the wrist depending on the size of the hook <NUM>, a value of the height difference H, and the size of the carabiner <NUM>, upward and downward angles β1, β2 from a horizontal plane Hs for twisting the wrist to incline the lifting hook <NUM> may be smaller than the conventional angles γ1, γ2.

Although the horizontal hook <NUM> has been illustrated, the same applies to the vertical hook <NUM>, and it is necessary to twist the wrist to incline the vertical hook <NUM> at the time of detachment from the carabiner <NUM>(<NUM>).

The necessity of twisting the wrist to detach the hook <NUM> of the embodiment of the present invention from the carabiner <NUM> or <NUM> depends on the size of the hook <NUM>, the value of the height difference H, and the size of the carabiner <NUM>, <NUM>. In designing of the height difference H and the size of the lifting hook <NUM>, the angle β1 or β2 described above may be about <NUM>°, preferably about <NUM>°, most preferably about <NUM>°. In other words, the height difference H and the hook size of the lifting hook <NUM> may be designed such that when the hook <NUM> of the embodiment of the present invention is locked to or detached from the carabiner <NUM>, <NUM>, the worker twists the wrist to rotate the work tool by an angle of <NUM>° or less, preferably <NUM>° or less, and most preferably about <NUM>° to <NUM>°.

<FIG> show a lifting hook <NUM> of a preferable example. In the description of the lifting hook <NUM> of the example, the same reference numerals are used for substantially the same elements as those of the lifting hook <NUM> described with reference with <FIG> etc. <FIG> is a perspective view. <FIG> is a plan view. <FIG> is a side view of the lifting hook <NUM> placed on a horizontal plane. The lifting hook <NUM> is made by bending a lot having a circular cross section. As can be seen best in <FIG>, the lifting hook <NUM> is formed into a three-dimensional shape with base elements of the lifting hook <NUM>, i.e., the inner leg <NUM>, the outer leg <NUM>, and the connecting part <NUM>, associated with each other such that the outer leg <NUM> is located at a relatively high position. As a result, a degree of twist of the wrist can be reduced particularly when the worker detaches the hook from the carabiner. In other words, the degree of twist of the wrist can be reduced as compared to those having a non-three-dimensional shape. This three-dimensional shape is formed to be easily detachable in accordance with the size and shape of the carabiner and the work tool. Additionally, the lifting hook <NUM> is formed into a shape not only easily detachable but also easily lockable to the carabiner.

Referring to <FIG>, the lifting hook <NUM> has a three-dimensional shape when placed on a horizontal plane and viewed from the side, and the bent end 102a of the inner leg <NUM> and the bent end 104a of the outer leg <NUM> are located on the same horizontal plane. The inner and outer bent ends 102a, 104a form a pivot axis Axbase of the lifting hook <NUM> when inserted and assembled in the attachment holes <NUM> of the work tool TL. The lifting hook <NUM> can pivot around the pivot axis Axbase to take a use position projected from the work tool TL (<FIG>) and a retracted position housed in a recess <NUM> (<FIG>) of the work tool TL. The lifting hook <NUM> is shaped such that the inner leg <NUM> and the outer leg <NUM> form a height difference with respect to the pivot axis Axbase. Therefore, when the worker locks/detaches the hook to/from the carabiner, the degree of twist of the wrist can be reduced. The shape with the height difference is designed in accordance with the size and shape of the carabiner and the work tool.

A solid line of <FIG> shows a state before the outer leg <NUM> is assembled to the work tool TL. A virtual line of <FIG> shows a state after the lifting hook <NUM> is assembled to the work tool TL. The inner leg <NUM> of the lifting hook <NUM> is inclined in a direction toward the outer leg <NUM>, i.e., in a direction away from the worker's body side, from the bent end 102a toward the connecting part <NUM>. This inclination angle is indicated by reference numeral "θ1". As a result, the lifting hook <NUM> has a tapered shape in planar view.

Referring to <FIG>, the connecting part <NUM> extends in the lateral direction. The outer leg <NUM> includes the first portion 104sub functionally constituting a portion of the connecting part <NUM>, and the functional main portion 104main continuing from the first portion 104sub and located at a higher position to functionally constitute a main part, and the functional main portion 104main has a linear length. An angle between the first portion 104sub and the functional main portion 104main is indicated by reference numeral "α". The functional main portion 104main having a length is made up of a straight line substantially parallel to the inner leg <NUM> when viewed from the side.

The dimensions or angles of the parts of the lifting hook <NUM> of the example are listed as examples as follows.

The height difference H of the above (<NUM>) may be <NUM> or more and <NUM> or less so as to eliminate the need for twisting the wrist excessively (for example, at <NUM>°) at the time of locking/detaching of the lifting hook. Preferably, the height difference H may be <NUM> or more and <NUM> or less so that the wrist is optimally twisted, for example, a twisting operation of <NUM>° or less is sufficient. Most preferably, the height difference H may be <NUM> or more and <NUM> or less so that the twist of the wrist is almost not required (<NUM>° to <NUM>°). When the hook <NUM> is detached from the carabiner <NUM>, <NUM>, it is necessary to open the gate lever <NUM> against the spring force with the functional main portion 104main of the outer leg <NUM> while the inner leg <NUM> is inside the hook body <NUM>. Depending on the size of the carabiners <NUM>, <NUM>, if the height difference H is too large, it becomes difficult to open the gate lever <NUM> with the outer leg <NUM>, and when the hook <NUM> is retracted into the work tool TL, the hook <NUM> may not be housed unless the housing recess <NUM> (<FIG>) is made deeper.

When the lifting hook <NUM> is placed on a horizontal plane, the pivot axis Axbase formed by the inner and outer bent ends 102a, 104a is located on the horizontal plane, and the lifting hook <NUM> has a three-dimensional shape with the height difference H between the inner leg <NUM> and the functional main portion 104main of the outer leg <NUM>.

Regarding the inclination angle θ1 (<FIG>) of the inner leg <NUM> of the above (<NUM>), i.e., the included angle θ1 between the inner leg <NUM> and the bent end 102a, by setting this angle θ1 to a value smaller than <NUM>°, the hook <NUM> can be formed into a tapered shape in planar view (see <FIG>). By forming the hook <NUM> into a tapered shape in planar view, the range supported by the carabiner <NUM>, <NUM> is limited when the work tool TL is suspended as shown in <FIG>, which improves the stability of the work tool TL when the tool is suspended (increases stability when the worker moves). Additionally, at the time of a detachment operation as shown in <FIG> and <FIG> (when the gate <NUM> is pushed down by the outer leg <NUM> or when the functional main portion 104main passes over the nose part <NUM>), a distance can be increased between the inner leg <NUM> and the worker or the carabiner body <NUM>, so that the operability is improved.

Referring to <FIG>, when the lifting hook <NUM> is in the use position, an axis of the hook <NUM> projected from the work tool TL is indicated by "Axf". An axis Axout of the outer leg <NUM> is parallel to this axis Axf. An included angle θ2 between the outer leg <NUM> and the bent end 104a is <NUM>°. The inner leg <NUM> has an axis Axin inclined relative to the axis Axf of the hook <NUM>. Therefore, the inclination angle θ1 of the inner leg <NUM> is smaller than <NUM>°, so that the hook <NUM> has a tapered shape in planar view.

Any one of the following three configurations may be employed for forming the hook <NUM> into a tapered shape in planar view.

The side-view included angle α (<FIG>) between the first portion 104sub and the functional main portion 104main of the outer leg <NUM> of the above (<NUM>) is related to the operability when the outer leg <NUM> is moved along the carabiner body <NUM> under visual observation or preferably in a groping manner. When the included angle α is greater than <NUM>° and at least <NUM>° or less at the time of detachment as shown in <FIG> and <FIG>, the outer leg <NUM> can be hooked on the gate lever <NUM> of the carabiner <NUM>, <NUM> and easily detached. The included angle α is greater than <NUM>° and preferably <NUM>° or less, more preferably <NUM>° or less.

An example of the work tool TL equipped with the lifting hook <NUM> will be described with reference to <FIG>. The work tool TL shown in the figures is a rechargeable electric chainsaw <NUM>. <FIG> is a side view of the electric chainsaw <NUM>, <FIG> is a plan view, and <FIG> is a rear view of the electric chainsaw <NUM> viewed from the rear side.

The electric chainsaw <NUM> shown in the figures is already commercially available, and therefore only the overview thereof will be described. The electric chainsaw <NUM> has a main body <NUM> and a cutting attachment <NUM>. The attachment <NUM> includes a guide bar <NUM> and a saw chain <NUM> guided by the guide bar <NUM> when rotated.

A battery is housed in the main body <NUM> along with a drive source such as a motor and a control unit, and the motor is driven by electric power supplied from the battery. The main body <NUM> is provided with a center grip <NUM>. This type of the chainsaw <NUM> is called a "top handle type chainsaw", and the worker Wk can hold the center grip <NUM> to operate the chainsaw <NUM>.

The lifting hook <NUM> of the example is assembled to a rear end surface <NUM> of the chainsaw <NUM> in a retractable manner. <FIG> show a state when the lifting hook <NUM> is used, and the lifting hook <NUM> is positioned to project rearward from the rear end surface <NUM>. The chainsaw <NUM> is moved in directions indicated by an arrow X in <FIG>, i.e., in directions along a surface of the guide bar <NUM>, when a cutting process is performed.

The locking/detaching of the lifting hook <NUM> to/from the short-nose carabiner <NUM> or the long-nose carabiner <NUM> will hereinafter be described with reference to <FIG>.

<FIG> shows a preparation step for attaching the lifting hook <NUM> to the short-nose carabiner <NUM>. The worker Wk lifts the chainsaw <NUM> and laterally moves the chainsaw <NUM> to bring the chainsaw <NUM> closer to the body, so that the inner leg <NUM> is brought into contact with the gate lever <NUM>. <FIG> shows a step of inserting the inner leg <NUM> into the carabiner <NUM>, or specifically, the carabiner body <NUM>. This insertion step is performed by moving the chainsaw <NUM> downward. This causes the inner leg <NUM> to open the gate lever <NUM> against the spring force, and the inner leg <NUM> enters the inside of the carabiner body <NUM>. When this is finished, the gate lever <NUM> is automatically closed by the spring force.

As described with reference to <FIG> and <FIG>, the worker Wk moves the chainsaw <NUM> laterally inward and then lowers the chainsaw <NUM> to engage the hook <NUM> with the short-nose carabiner <NUM>. <FIG> shows a state of the chainsaw <NUM> suspended from the waist belt Wb.

<FIG> shows a first preparation step for detaching the lifting hook <NUM> from the short-nose carabiner <NUM>. The worker Wk lifts the chainsaw <NUM> to position the functional main portion 104main of the outer leg <NUM> to the level of height of the gate lever <NUM>. <FIG> shows a second preparation step. The worker Wk laterally moves the chainsaw <NUM> toward the body side to bring the functional main portion 104main of the outer leg <NUM> into contact with the gate lever <NUM>.

Subsequently, the worker Wk lowers the chainsaw <NUM>. As a result, the gate lever <NUM> is opened by the outer leg <NUM> moving downward, and the outer leg <NUM> enters the inside of the carabiner body <NUM> (<FIG>). As a result, the hook <NUM> can be located inside the carabiner body <NUM>. Subsequently, the worker Wk can move the chainsaw <NUM> forward to pull out the hook <NUM> from the carabiner body <NUM>.

As described above, the worker Wk can move the chainsaw <NUM> laterally inward, then lower the chainsaw <NUM>, and move the chainsaw <NUM> forward to release the chainsaw <NUM> from the short-nose carabiner <NUM>. This series of operations may be performed while the worker is visually observing the operations or may be performed in a groping manner.

<FIG> shows a preparation step for attaching the lifting hook <NUM> to the long-nose carabiner <NUM>. The worker Wk lifts the chainsaw <NUM> and laterally moves the chainsaw <NUM> toward the body side to move the inner leg <NUM> to the inner side relative to the nose extension part <NUM>. Subsequently, the chainsaw <NUM> is lowered to bring the inner leg <NUM> into contact with the gate lever <NUM> (<FIG>). This completes the preparation for attachment. When the worker Wk then lowers the chainsaw <NUM> further downward, the gate lever <NUM> is opened by the inner leg <NUM>, and the inner leg <NUM> enters the inside of the carabiner body <NUM> (<FIG>).

As described with reference to <FIG>, the worker Wk lifts the chainsaw <NUM>, moves the chainsaw <NUM> laterally inward, and then moves the chainsaw <NUM> downward to engage the lifting hook <NUM> with the long-nose carabiner <NUM>. This series of operations may be performed while the worker is visually observing the operations or may be performed in a groping manner.

The worker Wk lifts the chainsaw <NUM> (<FIG>) and laterally moves the chainsaw <NUM> toward the body side to move the outer leg <NUM> to the inner side relative to the nose extension part <NUM> (<FIG>). Subsequently, the chainsaw <NUM> is lowered to open the gate lever <NUM> with the functional main portion 104main of the outer leg <NUM>, and the outer leg <NUM> is put into the carabiner body <NUM>. As a result, both the inner and outer legs <NUM>, <NUM> are located inside the carabiner body <NUM>.

Subsequently, the worker Wk can pull out the hook <NUM> from the carabiner body <NUM> by moving the chainsaw <NUM> forward.

As described above, the worker Wk can lift the chainsaw <NUM>, then move the chainsaw <NUM> laterally inward, then lower the chainsaw <NUM>, and move the chainsaw <NUM> forward to release the chainsaw <NUM> from the long-nose carabiner <NUM>. This series of operations may be performed while the worker is visually observing the operations or may be performed in a groping manner.

Referring to <FIG>, when the lifting hook <NUM> is disposed on the chainsaw <NUM>, the hook <NUM> is preferably offset closer to the worker as compared to the center grip <NUM>. As a result, when the hook <NUM> is locked to and detached from the carabiner <NUM>, <NUM>, or particularly when the hook <NUM> is detached (when the worker brings the work tool TL close to the body and uses the outer leg <NUM> to open the gate <NUM> of the carabiner <NUM>, <NUM>), the worker's body is made farther from the work tool TL, so that the worker and the work tool TL are not too close to each other, and the worker's body and the work tool TL hardly come into contact each other, which improves workability.

Referring to <FIG>, reference numeral "Axg" denotes a vertical axis of the chainsaw <NUM> when the worker grips the center grip <NUM> and lifts the chainsaw <NUM>. "E" denotes a horizontal plane such as the ground. In the chainsaw <NUM>, the pivot axis Axbase of the hook <NUM> is set to be located horizontally and made orthogonal to the vertical axis Axg of the chainsaw <NUM>.

The hook <NUM> is disposed at the rear end in the longitudinal direction of the work tool TL and is located near the middle in the up-down direction. As a result, since the work tool TL is directed straight downward when suspended, the work tool TL is less likely to interfere with the worker. Additionally, when locking/detaching the hook to/from the carabiner, the worker lifts the work tool to about <NUM>° for locking/detaching, resulting in favorable workability.

The included angle α between the first portion 104sub and the functional main portion 104main of the outer leg <NUM> gives a signal to the worker in a groping state. By setting the included angle α larger than <NUM>°, the inner leg <NUM> of the carabiner <NUM>, <NUM> can smoothly be moved in the carabiner body <NUM>, and the operation can smoothly be performed at the time of locking/detaching of the lifting hook <NUM>.

The lifting hook of the embodiment according to the present invention is preferably applicable to any hand-held work tool including a drive source. The drive source may be an internal combustion engine or an electric motor. Specific examples include a top handle type chainsaw and a chainsaw operated with both hands. Other major application examples are as follows:.

The brush cutter is generally operated with a main body held by both hands. When the lifting hook <NUM>, <NUM> is locked to and detached from the carabiner <NUM>, <NUM> while the brush cutter is held by both hands, the lifting hook <NUM>, <NUM> is preferably disposed on the brush cutter so that the height difference H is formed between the inner leg <NUM> and the outer leg <NUM> while the worker is in the most natural posture and wrist state.

<FIG> are views for explaining multiple modifications. <FIG> is a side view corresponding to <FIG> related to the lifting hook <NUM> and shows a lifting hook <NUM> of a first modification. In this lifting hook <NUM>, the outer leg <NUM> includes the inclined first portion 104sub as in the hook <NUM> of <FIG>; however, the functional main portion 104main having a length is relatively short, and an inclined third portion 104C is included between the functional main portion 104main and the bent end 104a. The third portion 104C is inclined downward and leads to the bent end 104a.

<FIG> shows a lifting hook <NUM> of a second modification. In the lifting hook <NUM>, the functional main portion 104main having a length has a rounded shape when viewed from the side, and the functional main portion 104main smoothly continues to the third portion 104C. The round-shaped functional main portion 104main is disposed relatively close to the connecting part <NUM>. The included angle α between the first portion 104sub and the functional main portion 104main is preferably greater than <NUM>°.

<FIG> shows a lifting hook <NUM> of a third modification. This lifting hook <NUM> has the round-shaped functional main portion 104main as in the second modification (<FIG>); however, the second modification is different in that the functional main portion 104main is disposed relatively close to the bent end 104a (<FIG>). In this third modification, the included angle α between the first portion 104sub and the functional main portion 104main is preferably greater than <NUM>°.

Claim 1:
A system comprising a lifting hook (<NUM>, <NUM>,<NUM>, <NUM>, <NUM>) and a work tool (TL) with a power source, the lifting hook comprising:
an inner leg (<NUM>) and an outer leg (<NUM>) fixed to the work tool (TL) with the power source; and
a connecting part (<NUM>) connecting free ends of the inner and outer legs (<NUM>, <NUM>) to each other, wherein
when a worker equipped with a lever-type carabiner (<NUM>, <NUM>) holds the work tool (TL), the inner leg (<NUM>) of the lifting hook is located on the inner side close to the carabiner (<NUM>, <NUM>) while the outer leg (<NUM>) is located on the outer side far from the carabiner (<NUM>, <NUM>), wherein
the inner and the outer leg (<NUM>, <NUM>) include respective bent ends (102a, 104a) forming a pivot axis (Axbase) of the lifting hook (<NUM>, <NUM>), wherein
the lifting hook (<NUM>) is shaped such that when the lifting hook (<NUM>) is placed on a horizontal plane and the bent ends (102a, 104a) are located on the horizontal plane, the inner leg (<NUM>) and the outer leg (<NUM>) have a height difference (H) with respect to the pivot axis (Axbase) so that at least a portion of the outer leg (<NUM>) is located higher than the inner leg (<NUM>), and wherein
since the inner leg (<NUM>) and the outer leg (<NUM>) have the height difference (H), the inner leg (<NUM>), the connecting part (<NUM>), and the outer leg (<NUM>) form a three-dimensional shape.