BJÖRNLINGER, Johan (Kittendorffs Gata 20, Huskvarna, S-561 51, SE)
MARTINSSON, Pär (Orrvagen 4, Jόnkόping, 556 26, SE)
RACOV, Mikael (Blomodlarevagen 17, Lekeryd, 560 28, SE)
SVENNUNG, Johan (Norgardsgatan 4A, Jόnko in, 55336, SE)
BERGQUIST, Oskar (Skolgatan 30A, S- Huskvarna, 561 35, SE)
BJÖRNLINGER, Johan (Kittendorffs Gata 20, Huskvarna, S-561 51, SE)
MARTINSSON, Pär (Orrvagen 4, Jόnkόping, 556 26, SE)
RACOV, Mikael (Blomodlarevagen 17, Lekeryd, 560 28, SE)
SVENNUNG, Johan (Norgardsgatan 4A, Jόnko in, 55336, SE)
| CLAIMS An electric power tool (100, 200) comprising: a handle section (104, 208) comprising at least one handle (104, 106, 212); at least one working implement positioned at least partly in front of the handle section (104, 208) along a longitudinal axis L of the electric power tool (100, 200); an electric drive motor drivably connected to the at least one working implement; at least one battery (112, 214) connected to the electric drive motor for supplying electrical energy, wherein the battery (112, 214) is located at least partially backwards from the handle section (104, 208) along the longitudinal axis L and the battery (112, 214) comprises at least one battery cell (126) encased in a cell housing (124); the cell housing (124) being provided with one or more electrical contacts (128) and at least one mechanical mating surface to electrically and mechanically connect the battery (112, 214) to the electric power tool (100, 200), characterized in that, the battery (112, 214) is protected by a protection housing (132, 226), wherein the protection housing (132, 226) extends beyond the battery (112, 214) in a substantially rearward direction along the longitudinal axis L. An electric power tool (100, 200) according to claim 1, wherein the protection housing (132, 226) encloses the battery (112, 214) on at least one side. An electric power tool (100, 200) according to claim 2, wherein the protection housing (132, 226) encloses the battery (112, 214) on at least two sides. An electric power tool (100, 200) according to claim 2, wherein the protection housing (132, 226) encloses the battery (112, 214) on at least four sides. An electric power tool (100, 200) according to claim 1, wherein the protection housing (132, 226) is a single wall located rearwards of the battery (112, 214) along the longitudinal axis L. 6. An electric power tool (100, 200) according to claim 1, wherein the protection housing (132, 226) is integral with the electric power tool (100, 200). 7. An electric power tool (100, 200) according to any one of the claims 1 to 6, wherein the protection housing (132, 226) comprises thermal insulating material. 8. An electric power tool (100, 200) according to any one of the claims 1 to 7, wherein the protection housing (132, 226) comprises openings to improve the ventilation of the battery (112, 214). 9. An electric power tool (100, 200) according to any one of the claims 1 to 8, wherein the handle section (104, 208) includes at least a front handle (104, 210) and a rear handle (108, 212). 10. An electric power tool (100, 200) according to any one of the claims 1 to 9, wherein the electric power tool (100, 200) is one of a chain saw (100), a line trimmer (200) or a hedge trimmer. |
TECHNICAL' FIELD
The present invention relates to an electric power tool. In particular, the present invention relates to an electric power tool which is powered by a battery.
BACKGROUND
Hand-held electric power tools such as, but not limited to, chain saws, line trimmers, and hedge trimmers that are powered by batteries are well known in the art. The battery is usually positioned behind a rear handle of an electric power tool for improved balance and stability during operation.
Typically, the battery includes multiple electrochemical cells encased within a cell housing. The battery housing includes electrical contacts to electrically couple the battery with the electric power tool when the battery is mounted.
U.S. Pat. No. 5,685,080 issued on November 1 1, 1997 and assigned to Makita Corporation, titled "Battery powered chain saw " describes a battery powered chain saw in which the battery is detachably mounted at a rear end of a handle housing. U.S. Design Pat. No. 575,605 issued on August 26, 2008 and assigned to Makita Corporation, titled "Portable electric chain saw " illustrates a chain saw with the battery mounted behind the rear handle. Another, U.S. Design Pat. No. 434,620 issued on December 05, 2000 and assigned to The Toro Company, titled "Housing for a hedge trimmer" illustrates a battery housing for a hedge trimmer in which the battery is partially inserted. The battery housing is located behind the rear handle. In the aforementioned U.S. patents, some portion of the battery is directly exposed to the ambient environment and may get damaged by mechanical impacts, in particular from the rear, as well as by adverse elements, such as extreme temperatures, moisture, particulate matter etc. Very low temperatures may cool down the battery and reduce its efficiency. Since the electrical contacts of the battery are also not completely protected, moisture and particulate matter may have a detrimental effect on them and may cause short circuit and reduce battery life. In light of the foregoing, there is a need for a hand-held electric power tool that safeguards the battery against mechanical impacts and adverse environmental conditions.
SUMMARY
In view of the above, it is an objective of the present invention to solve or at least reduce the problems discussed above. In particular, the objective is to provide an improved electric power tool, which is powered by a battery, such that the battery is protected against mechanical impacts and harmful environmental elements or conditions.
The objective is at least partially achieved according to a novel electric power tool described in claim 1. The electric power tool includes a handle section comprising at least one handle and at least one working implement positioned at least partly in front of the handle section along a longitudinal axis of the power tool. An electric drive motor is drivably connected to the working implement, and at least one battery connected to the electric drive motor for supplying it with electrical energy. The battery is located at least partially backwards from the handle section along the longitudinal axis of the power tool. Further, the battery includes at least one battery cell encased in a cell housing. The cell housing is provided with electrical contacts and at least one mechanical mating surface to electrically and mechanically connect the battery to the power tool. Further, the battery is protected by a protection housing against mechanical impacts and harmful environmental elements or conditions. The battery protector extends beyond the battery in a substantially rearward direction along the longitudinal axis. Such a configuration substantially protects battery from mechanical impacts, especially from the rear.
According to claim 2, the protection housing encloses the battery on at least one side. According to claim 3, the protection housing encloses the battery on at least four sides, thereby protecting the battery on at least four sides. The at least four sides can include a front side, a rear side, a top side and a bottom side.
According to claim 4, the battery protector is a single wall located rearwards of the battery along the longitudinal axis. The single wall substantially protects the battery against accidental impacts from only one side.
According to claim 5, the battery protector is integral with the power tool. According to claim 6, the protection housing includes thermal insulating material to prevent cooling of the battery and thus, a decrease in battery efficiency.
According to claim 7, the protection housing includes openings to improve the ventilation of the battery.
According to claim 8, the handle section includes at least a front handle and a rear handle.
According to claim 9, the electric power tool may be one of a chain saw, a line trimmer, or a hedge trimmer.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will in the following be described in more detail with reference to the enclosed drawings, wherein:
FIG. 1 A illustrates a rear perspective view of an electric power tool, according to an embodiment of the present invention;
FIG. IB illustrates a side elevation view of an electric power tool, according to an embodiment of the present invention;
FIG. 1C illustrates a sectional view of an electric power tool, according to an embodiment of the present invention;
FIG. 2A illustrates a perspective view of a line trimmer, according to an embodiment of the present invention; and
FIG. 2B illustrates a side elevation view of a line trimmer, according to an embodiment of the present invention.
DESCRIPTION OF EMBODIMENTS
The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which example embodiments of the invention incorporating one or more aspects of the present invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. For example, one or more aspects of the present invention can be utilized in other embodiments and even other types of devices. In the drawings, like numbers refer to like elements. FIGS. 1A and IB illustrate two views of an example chain saw 100, according to an embodiment of the present invention. The chain saw 100 (hereinafter referred to as the "electric power tool 100") may be used in gardening or forestry applications. However, the present invention may also be used in any other battery powered equipment, for example, line trimmers, hedge trimmers, drills, reciprocating saws, rotary saws, power screw drivers, or other cutting or pruning tools without departing from the essence of the present invention. In addition, any suitable size, shape or type of elements or materials could be used. Further, as used herein, the terms "longitudinal direction" and "transverse direction" indicate a direction relative to the electric power tool 100. The term "longitudinal direction", without further specificity, is a reference to a direction parallel to a longitudinal axis L of the electric power tool 100. The term "transverse direction", without further specificity, is a reference to a direction perpendicular to the longitudinal axis L when viewed from the top i.e., substantially perpendicular to the plane of the paper in a side view. The terms "front side" and "rear side" of any component or portion of the electric power tool 100 may in general refer to sides of the component or portion that are substantially along the longitudinal axis L, the "front side" being further from a user than the "rear side" during operation of the electric power tool 100. The terms "top side" and "bottom side" of any component or portion may in general refer to sides substantially perpendicular to the longitudinal axis L, the "top side" and the "bottom side" being at the top and the bottom sides of the component or portion respectively.
The electric power tool 100 includes a tool body 102 and working implements (not shown). The tool body 102 may include a handle section 104 to enable a user to hold and manipulate the electric power tool 100. In an embodiment of the present invention, the handle section 104 may include a front handle 106 and a rear handle 108. The rear handle may include a grip portion 109 to aid in manual grasping of the electric power tool 100. The front handle 106 and the rear handle 108 may include vibration absorbing means, such as springs, one or more rubber members, or the like. The front handle 106 may be mounted such that the front handle 106 may be adjustable in a linear and/or angular manner. A guard 110 may be present to safeguard a user during operation of the electric power tool 100. In an embodiment of the present invention, the working implements may include a toothed chain supported on a guide bar. The guide bar may be attached to the tool body 102 via one or more fasteners. A drive sprocket and an idler sprocket may be present at a proximate end and a distal end of the guide bar respectively with respect to the tool body 102. In an embodiment of the present invention, during an operation of the electric power tool 100, the drive sprocket is driven by an electric drive motor (not shown) via suitable transmission means, for example, but not limited to, one or more gears, belt drive, friction drive, or any combination of these. The transmission means may be utilized to selectively drive the dive sprocket at one or more speeds. The electric drive motor may be an electrically powered motor, such as, but not limited to, AC motor, DC motor, or the like. In an embodiment of the present invention, the speed and torque of the electric motor may be continuously or discretely varied by suitable control means. The control means may include one or more sensors to sense various parameters of the electric drive motor, for example, speed, torque etc. The sensed parameters may then be utilized to control the speed and/or torque of the electric drive motor. In an embodiment of the present invention, the electric drive motor is selectively supplied with electrical energy by a battery 112 depending on the activation or deactivation of an on/off switch 114. The rated power and other specifications of the electric drive motor and/or the battery 112 may be selected based on various parameters, for example, power requirements, operational durations, expected life, cost, weight, dimensions etc.
As shown in FIGS. 1A and IB, the battery 112 is located backwards of the handle section 104 along the longitudinal axis L. In other embodiments of the present invention, only some portions of the battery 112 may be located backwards of the handle section 104 along the longitudinal axis L whereas one or more portions of the battery 112 may be located substantially in the transverse direction with respect to the handle section 104. In an embodiment of the present invention, the battery 112 may be detachably attached to the tool body 102 of the electric power tool 100 to aid in charging, maintenance, and/or storage. However, in other embodiments of the present invention, the battery 112 may be fixedly attached to the electric power tool 100. In an embodiment of the present invention, the battery 112 may include at least one handle (not shown) to aid in manual handling of the battery 112.
FIG. 1C illustrates a sectional view of the electric power tool 100, according to an embodiment of the present invention. The battery 112 includes a cell housing 124 which may encase one or more battery cells 126.Though in the example embodiment, the battery cells 126 are shown to be stacked substantially parallel to each other in multiple columns, other configurations (e.g., staggered) can be envisioned without departing from the essence of the present invention. One or more battery cells 126 may also be placed adjacent to one another in a transverse direction. The one or more battery cells 126 may be rechargeable Lithium-Ion cells. Inner surfaces of the cell housing 124 may include electrical conductors to connect poles of the one or more battery cells 126 to one or more electric contacts 128. The one or more electric contacts 128 may extend at least partially in the transverse direction. In an embodiment of the present invention, the one or more electric contacts 128 may engage with corresponding electrical contacts provided in the tool body 102 to form electrical connections. The battery 112 may also include at least one mechanical mating surface (not shown) to mechanically connect the battery 112 to the tool body 102 of the electric power tool 100. The mechanical mating surface may include suitable releasable mechanical connections, for example, but not limiting to, snap-fit connections, mating recesses and grooves, connections with resilient members (e.g., springs), or a combination of any of these.
In an embodiment of the present invention, a protection housing 132 may be provided to safeguard the battery 112 against mechanical shocks and external elements, such as moisture, particulate matter etc. The protection housing 132 may extend beyond the battery 112 in a substantially rearward direction along the longitudinal axis L. As shown in FIGS. 1A-1C, the protection housing 132 may enclose the battery 112 at least partially on two sides, namely, an upper side, and a rear side, with respect to the longitudinal axis L. However, in other embodiments of the present invention, the protection housing 132 may enclose the battery 112 at least partially on one or more sides. In still other embodiments of the present invention, the protection housing 132 may enclose the battery 112 least partially on at least four sides.
The protection housing 132 may have various configurations without departing from the essence of the present invention, for example, but not limiting to, a one-piece configuration, a modular configuration with one or more shells, or the like. In an embodiment of the present invention, the protection housing 132 may be integrally formed with the tool body 102 of the electric power tool 100. In another embodiment of the present invention, the protection housing 132 may be separately formed and then attached to the electric power tool 100. The protection housing 132 may also be detachably attached to the tool body 102 to aid in repair or maintenance. The protection housing 132 may be manufactured by various processes, such as moulding, forming, machining, or the like.
The protection housing 132 may be made of a suitable material, such as metal or plastic. In an embodiment of the present invention, the protection housing 132 may be made of a thermally insulating material or may include a thermally insulating coating to prevent a cooling of the battery 112 and thus, a decrease in the battery efficiency in inclement environmental conditions (e.g., low temperature). In another embodiment of the present invention, the protection housing 132 may include suitable sealing members (e.g., sealing rings) to impede the entry of moisture, particulate matter etc., thereby protecting the electrical contacts of the battery 112 and/or the tool electrical contacts from erosion or short circuit. The protection housing 132 may further include one or more openings (not shown in the figures) to improve the ventilation of the battery 112. The openings may be selectively opened or closed depending on various parameters, such as ambient temperature, ambient humidity or moisture conditions (e.g., rain) etc. The protection housing 132 may also include shock absorbing members (not shown in the figures), for example, rubber pads, springs etc.
In various embodiments of the present invention, the protection housing 132, may at least partially enclose the battery 112 to permit the insertion of the battery 112 from the rear substantially parallel to the longitudinal axis L. In an embodiment of the present invention, the protection housing 132 may include a first wall (not shown) and a second wall (not shown) that at least partially enclose the battery 112 on a lateral side and a front side respectively, such that the lateral side is substantially parallel to and offset from the longitudinal axis L. The first wall may extend beyond the battery 112 in a substantially rearward direction along the longitudinal axis L. In an embodiment of the present invention, at least one of the first wall and the second wall may extend the battery 112 in a direction perpendicular to both of the longitudinal direction and the transverse direction. In another embodiment of the present invention, an additional wall (not shown) may enclose the battery 112 on the top side or the bottom side. In an embodiment of the present invention, a single wall (not shown), which is located rearwards of the battery 112 along the longitudinal axis L, may form the protection housing and protect the battery 112 from rear impacts. However, in other embodiments of the present invention, the single wall may be placed on any other side of the battery 112, such as the front side, bottom side, or the top side of the battery 112.
FIGS. 2 A and 2B illustrate a line trimmer 200, according to an embodiment of the invention. The line trimmer 200 includes a main body 202, a shaft 204 and a cutting assembly (not shown). The main body 202 includes a rear handle 212 while a front handle 210 may be provided on the shaft 204. In an embodiment of the present invention, the front handle 210 and the rear handle 212 may together be a part of handle section 208. A rechargeable battery 214 may be removably attached to the main body 202 at least partially backwards from the handle section 208 along the longitudinal axis L. In other embodiments of the present invention, the battery 214 may be fixedly attached to the line trimmer 200. The cutting assembly may include an electric drive motor which drives one or more working implements. The electric drive motor may be electrically connected to the battery 212 via one or more conductors (not shown). The one or more working implements may include one or more cutting means, for example, but not limited to, filament cutters, cutter blades, or the like.
In an embodiment of the present invention, the main body 202 may include a protection housing 226 which may extend beyond the battery 214 in a substantially rearward direction along the longitudinal axis L. As shown in FIGS. 2A and 2B, the protection housing 226 may enclose the battery 214 at least partially on two sides, namely, an upper side, and a rear side, with respect to the longitudinal axis L. However, in other embodiments of the present invention, the protection housing 226 may enclose the battery 214 at least partially on one or more sides. In still other embodiments of the present invention, the housing 226 may enclose the battery 214 at least partially on at least four sides.
The details of the line trimmer 200 shown in FIGS. 2 A and 2B are for illustrative purposes only and it may be evident to a person ordinarily skilled in the art that the line trimmer 200 may be of various configurations and shapes without deviating from the present invention. In the drawings and specification, there have been disclosed preferred embodiments and examples of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation, the scope of the invention being set forth in the following claims.