Patent Application
20110162219
This application claims priority to Japanese Patent Application No. 2010-000124 filed on Jan. 4, 2010, the contents of which are hereby incorporated by reference into the present application.
The present application relates to handheld power tools that include, but are not limited to, electric chain saws, electric circular saws and electric blowers. Especially, the present application relates to a type of handheld power tools with a top grip or a top handle disposed on a top portion of its main body.
JP 2008-55711 A discloses an electric chain saw. The electric chain saw is a type of handheld electric power tools with a top grip. The electric chain saw comprises a saw chain and a main body having a guide bar for the saw chain. A motor is housed in the main body and configured to drive the saw chain. A battery interface configured to detachably receive a battery pack is disposed in a back portion of the main body. The top grip is provided on a top portion of the main body.
In the aforementioned power tool with the top grip, weight distribution with respect to the top grip is important. If a center of gravity of the power tool is horizontally offset with respect to a center axis of the top grip, the electric power tool will lean when a user holds the power tool at the top grip. Such imbalance causes inconvenience to the user.
Accordingly, it is an object of the present teachings to provide a technique for improving the weight distribution with respect to the top grip or the top handle.
Generally, a battery pack for an electric power tool is large and heavy. Therefore, the conventional power tool is designed such that, in a planar view of the main body, the center of gravity of the battery pack is located on a straight line passing through the center axis of the top grip. With this design, the heavy battery pack is prevented from influencing the weight distribution of the power tool with respect to the top grip.
On the contrary, the present teachings proposes a new design in which the battery pack is arranged to be horizontally displaced with respect to the center axis of the top grip. With this design, the weight distribution of the power tool may be drastically improved by using the heavy weight of the battery pack such that the center of gravity of the power tool is located on the straight line passing through the center axis of the top grip.
In one aspect of the present teachings, a handheld power tool may comprise a main body supporting a tool. A motor may be housed in the main body and configured to drive the tool. A battery interface may be disposed on a rear portion of the main body and configured to detachably receive a battery pack. A top grip may be provided on a top portion of the main body. In a planar view of the power tool, the top grip may extend along a front-to-rear direction of the main body and the center of gravity of the battery pack attached to the battery interface may be located at one side of a straight line passing through the center axis of the top grip.
In one embodiment of a handheld electric power tool of the present teachings, a motor may be disposed at one side of a straight line passing through a center axis of a top grip in a planar view. In this case, a battery pack may be preferably disposed at an opposite side of the motor with respect to the straight line passing through the center axis of the top grip. That is, in the planar view of the power tool, a center of gravity of the battery pack and a center of gravity of the motor may be preferably located at the opposite side of each other with respect to the straight line passing through the center axis of the top grip. In this design, a relatively heavy weight of the motor may at least partly be cancelled with the weight of the battery pack.
In one embodiment of the present teachings, the power tool may comprise an oil tank housed in the main body. In this case, a center of gravity of the oil tank may preferably be located at the opposite side of the center of gravity of the motor with respect to the straight line passing through the center axis of the top grip in the planar view of the power tool. In this design, the relatively heavy weight of the motor may at least partly be cancelled with the weight of the oil tank, which may improve the weight distribution of the power tool with respect to the top grip.
In one embodiment of the invention, the battery interface may be configured to receive an adapter for connecting the power tool to an AC power source in replacement of the battery pack. In this case, note that the weight distribution of the power tool may relatively change in the front-to-rear direction between a state where the battery pack, being relatively heavy, is attached and a state where the adapter, being relatively light, is attached. Accordingly, if the weight distribution of the power tool is optimized with the battery pack attached, the center of gravity of the power tool will lean frontward when the adapter is attached in replacement of the battery pack. Likewise, if the weight distribution of the power tool is optimized with the adapter attached, the center of gravity of the power tool will lean rearward when the battery pack is attached in replacement of the adapter.
Accordingly, in the embodiment of the present teachings, the power tool is preferably designed such that the main body leans rearward when the main body is held at the top grip with the battery pack attached to the battery interface and the main body leans frontward when the main body is held at the top grip with the adapter attached to the battery interface.
In this configuration, the power tool is intentionally allowed to lean to a certain degree in each state of the battery pack or the adapter attached, which may prevent the power tool from leaning beyond to an permitted degree in each condition of the battery pack or the adapter attached.
In the above configuration, the center of gravity of the motor may preferably be located rearward with respect to a position where a middle finger is arranged when the user grasps the top grip. With this configuration, it may be easy to embody the weight distribution mentioned above without rearrangement of other components.
The aforementioned designs and configurations may preferably apply to the chain saw that comprises a saw chain and a main body having a guide bar for the chain saw, however, are not limited to such an application.
Representative, non-limiting examples of the present invention will now be described in further detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Furthermore, each of the additional features and teachings disclosed below may be utilized separately or in conjunction with other features and teachings to provide improved electric power tools, as well as methods for using and manufacturing the same.
Moreover, combinations of features and steps disclosed in the following detail description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe representative examples of the invention. Furthermore, various features of the above-described and below-described representative examples, as well as the various independent and dependent claims, may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings.
All features disclosed in the description and/or the claims are intended to be disclosed separately and independently from each other for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter, independent of the compositions of the features in the embodiments and/or the claims. In addition, all value ranges or indications of groups of entities are intended to disclose every possible intermediate value or intermediate entity for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter.
Referring the drawings, a chain saw 10 of a specific embodiment will be described below. The chain saw 10 of the present embodiment is a type of handheld electric power tool for cutting a timber. As shown in
The main body 20 is provided with a guide bar 22. The guide bar 22 extends frontward (rightward in
A motor 34 is housed in the main body 20. The motor 34 is connected to the aforementioned sprocket and drives the saw chain 12 around the guide bar 22 by rotating the sprocket. As shown in
The main body 20 is provided with a battery interface 32. The battery interface 32 is configured to removably receive the battery pack 50. The battery interface 32 is arranged at a rear portion of the main body 20 (left portion in
The main body 20 is provided with a top grip 28 and a front grip 26. The top grip 28 and the front grip 26 are configured to be grasped by a user. As shown in
The top grip is provided with a trigger 30 that is operated by the user to activate and deactivate the motor 34. The trigger 30 normally is operated with an index finger of the right hand grasping the top grip 28. In this case, a middle finger of the right hand is located at a position P shown in
The main body 20 further includes an oil tank 36. The oil tank 36 is configured to store lubricant oil and supply the stored lubricant oil to the sprocket and saw chain 12. The oil tank 36 is provided with an oil cap 38. The oil cap 38 is configured to be removed when the user feeds the oil tank 36 with the lubricant oil. A dot G36 shown in
Furthermore, a hanging ring 40 is provided to the main body 20. The hanging ring 40 is attached to a bottom portion of the main body 20. The hanging ring 40 is configured capable of shifting between an outer position where the hanging ring 40 is put out from the main body 20 and an inner position where the hanging ring 40 is substantially housed within the main body 20. Note that
Hereinbefore the overall structure of the chain saw 10 has been described. Hereinafter specific features of the chain saw 10 will be described. As shown in
In addition, as shown in
The above-mentioned features relate to weight distribution of the chain saw 10 in the right-to-left direction. Next, weight distribution of the chain saw 10 in the front-to-rear direction will be described. As shown in
Comparing the battery pack 50 and the adapter 60, the battery pack 50 is larger and heavier than the adapter 60 and a difference of weight between them is relatively large. Accordingly, the weight distribution of the chain saw in the front-to-rear direction may significantly change between a case where the battery pack 50 is attached to the main body 20 and a case where the adapter 60 is attached to the main body 20. If the weight distribution of the chain saw 10 is optimized with the battery pack 50 attached, the chain saw 10 leans frontward when the adapter 60 is attached in replacement of the battery pack 50. Similarly, if the weight distribution is optimized with the adapter 60 attached, the chain saw 10 leans backward when the battery pack 50 is attached in replacement of the adapter 60.
Therefore, the chain saw 10 of the present embodiment is designed so as to lean backward when the chain saw 10 is held at the top grip 28 with the battery pack 50 attached to the battery interface 32 and to lean frontward when the chain saw 10 is held at the top grip 28 with the adapter 60 attached to the battery interface 32. In detail, as shown in
As described above, the chain saw 10 is designed to lean backward when the relatively heavy battery pack 50 is attached, which prevent the chain saw 10 from largely leaning to the front side when the relatively light adapter 60 is attached. In other words, the chain saw 10 is designed to lean frontward when the relatively light adapter 60 is attached, which prevents the chain saw 10 from greatly leaning to the back side when the relatively heavy battery pack 50 is attached. Thus, the chain saw 10 is designed to lean frontward and backward with a certain degree when the battery pack 50 and the adapter 60 is attached respectively. As a result, the chain saw 10 is prevented from leaning to the front and back side beyond a permissive degree. Here, the chain saw 10 of the present embodiment is designed such that the aforementioned angles A1 and A2 do not exceed 15 degrees respectively.
Hereinafter another feature of the chain saw 10 of the present embodiment will be described. As previously described, the main body 20 is provided with the hanging ring 40.
The stopper pin 48 is arranged inside of the hanging ring 40 and prevents the hanging ring 40 from coming off from the storage space 44. That is, the hanging ring 40 can move out from the main body 20 to the outer position where the stopper pin 48 contacts with the hanging ring 40. When the hanging ring 40 moves the outer position, the hanging ring 40 is supported by the stopper pin 48, an opening 42 of the storage space and the positioning pin 46.
The positioning pin 46 is configured to contact with the hanging ring 40 from the outside. The positioning pin 46 has a surface which is made of rubber and elastically deformed in contact with the hanging ring 40. When the hanging ring 40 moves to the outer position, the positioning pin 46 keeps the hanging ring 40 in the outer position with the elastic force. In addition, when the hanging ring 40 moves to the inner position, the elastic force of the positioning pin 46 turns over and works to keep the hanging ring 40 in the inner position.
As described above, the hanging ring 40 is disposed within the storage space 44 and is supported by the stopper pin 48 from the inside. According to this configuration, when the hanging ring 40 is struck against a floor or wall, the hanging ring 40 can be retracted in various directions according to a direction of the striking. Thus, the hanging ring 40 and the holding structure for the hanging ring 40 of the main body 20 are effectively prevented from breaking and being damaged.
Additionally, in the present embodiment, when the hanging ring 40 is stored in the storage space 44, the hanging ring 40 is not entirely housed within the storage space 44 but a part of the hanging ring 40 is out of the storage space 44. According to this configuration, the user directly puts his/her fingers on the hanging ring 40 housed within the storage space 44 and easily moves it to the outer position.
Furthermore, in the present embodiment, when the hanging ring 40 moves to the outer position, the hanging ring 40 is kept in the outer position by the elastic force of the positioning pin 46. By keeping the hanging ring 40 in the outer position, the user can easily tie a rope or belt to the hanging ring 40. The positioning pin 46 is also configured to keep the hanging ring 40 in the inner position by the elastic force when the hanging ring 40 moves to the inner position. By keeping the hanging ring 40 in the inner position, the hanging ring 40 is prevented from striking a floor or wall in advance.
Specific embodiment of the present teachings is described above, but this merely illustrates some representative possibilities for utilizing the teachings and does not restrict the claims thereof. The subject matter set forth in the claims includes variations and modifications of the specific examples set forth above. For example, the technique of the present embodiment regarding weight distribution can be applied to various types of handheld electric power tools including, but not limited to, an electric circular saw and an electric blower.
In the embodiment described above, the center line of the battery interface 32 arranged at a rear portion of the main body 20 is located, in the planer view of the main body 20, on the opposite side of the grip's centerline C28 in relation to the center of gravity G34 of the motor 34 (see
In another embodiment as shown in
Accordingly, there are plural and different designs resulting the center of gravity of the battery pack is arranged offset with respect to the straight line C28 in a planer view of the main body 20 from the top, in particular on the side opposite to the center of gravity G34 of the motor in relation to the grips' centerline C28. The same applies with respect to the attachment of the adapter 60 described with respect to
Furthermore, it is preferred to have a distance d≧5 mm of the center of gravity G50 or the center line of the battery interface, respectively, in a planer view of the main body from the top with respect to the straight line C28. Not withstanding the minimum distance, it is preferred to have a distance d in the range of 8 to 20 mm.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010-000124 | Jan 2010 | JP | national |
