WO2012128680A1

WO2012128680A1 - Battery pack for a battery powered tool

Info

Publication number: WO2012128680A1
Application number: PCT/SE2011/050308
Authority: WO
Inventors: Johan BJÖRNLINGER; Oskar Bergquist
Original assignee: Husqvarna Ab
Priority date: 2011-03-22
Filing date: 2011-03-22
Publication date: 2012-09-27
Also published as: DE112011105074T5; CN103442856A

Abstract

The present invention relates to a battery pack (104) for a battery powered tool (100). The battery pack (104) includes a plurality of battery cells (202) provided in at least two rows (206) with at least two battery cells (202) in each row (206). The rows (206) are placed on top of each other and each row (206) is displaced relative to each closest row, such that a parallelogram shaped cross-section of the battery pack (104) is formed. The battery pack (104) further includes at least one end row (208, 210) provided as the last row of battery cells on top or below the at least two rows (206), such that the at least one end row (208, 210) includes at least one battery cell (202) less than each of the at least two rows (206).

Description

Battery pack for a battery powered tool

Technical field

The present invention relates to a battery pack. In particular, the present invention relates to a battery pack for a battery powered tool.

Background

Battery powered hand held tools such as, but not limited to, chainsaws, line trimmers, hedge trimmers, rotary saws, or the like, are well known in the art. A detachable battery pack is usually used to provide electric energy to a prime mover (for example an electric motor) of a battery powered hand held tool.

Typically, the battery pack includes multiple cylindrical cells encased within a battery housing . In prior art battery packs, the cells are usually arranged in rows and columns in a substantially square or rectangular shape within the battery housing. However, such an arrangement may not provide a compact battery pack and the number of cells for a given volume within the battery housing may also not be optimally utilized. Moreover, a power transfer connector, which electrically connects the cells to electrical terminals provided on the battery powered tool, are provided on an outer surface of the battery housing and this further reduces the compactness of the battery pack. Such a battery pack, when attached to the battery powered tool, may result in poor handling and low ergonomics of the battery powered tool.

U.S. Patent No. 7,019,666 granted on March 28, 2006, titled "Adapter for a meter" and assigned to Tantalus Systems Corp., discloses a battery pack for an adapter of an electric meter. The U.S. Patent No. 7,019,666 further discloses battery cells being arranged such that the battery pack has a parallelogram shape. The parallelogram shape permits the battery pack to be inserted into a corresponding battery bay in only two orientations as opposed to four orientations in a square shaped battery pack. In this case, the parallelogram shape results in an effective configuration to electrically connect and disconnect the battery pack within the battery housing. Further, U.S. published application No. 2009/0226803 published on September 10, 2009, titled "Battery, battery pack and method of manufacturing connection terminal used therein", discloses a fire resistant battery pack. The battery pack disclosed in the U.S. published application No. 2009/0226803 has a parallelogram shape. However, the arrangements of battery cells disclosed in the aforementioned patent and published patent application may not be spatially optimal and not lead to a compact battery pack. In light of the foregoing, there is a need for a compact battery pack, for a battery powered tool, with an optimum arrangement of battery cells.

Summary

In view of the above, it is an objective to solve or at least reduce the problems d iscussed above. In particular, the objective is to provide a compact battery pack, for a battery powered tool, with an optimal arrangement of cells.

The objective is at least partially achieved with a novel battery pack for a battery powered tool according to claim 1 . The battery pack includes a plurality of battery cells provided in at least two rows with at least two battery cells in each row. The rows are placed on top of each other and each row is displaced relative to each closest row, such that a parallelogram shaped cross-section of the battery pack is formed. The battery pack further includes at least one end row provided as the last row of battery cells on top or below the at least two rows, such that the at least one end row includes at least one battery cell less than each of the at least two rows. Such an arrangement of the battery cells may lead to a compact configuration of the battery pack. Therefore, the battery pack may improve the handling and ergonomics of the battery powered tool.

According to claim 2, the battery cells in the at least one end row may be located such that the parallelogram shape is provided with a truncated corner. The tru ncated corner may fu rther result i n a more com pact configuration of the battery pack by removing at least one sharp corner from the parallelogram shape of the battery pack.

According to claim 3, the battery cells may be cylindrically shaped. Further, according to claim 4, the rows may be displaced relative to each closest row by a distance of half the diameter of a battery cell. A distance of half the diameter of a battery cell may provide the most compact arrangement of circular battery cells.

According to claim 5, two sides of the parallelogram shaped battery pack may form an angle of about 100-150 degrees, and preferably of about 1 10-1 30 deg rees . Fu rther, accord i ng to claim 6, two sides of the parallelogram shaped battery pack may form an angle of about 30-80 degrees, and preferably of about 50-70 degrees.

According to claim 7, two corners of the parallelogram shaped battery pack may be truncated. The two truncated corners may further result in a more compact configuration of the battery pack by removing two sharp corners from the parallelogram shape of the battery pack.

According to claim 8, the diameter of a battery cell may be in the range of about 10-25 millimeters, preferably of about 15-20 millimeters, and more preferably of about 18 millimeters. Alternatively, according to claim 9, the battery cells may have a length in the range of about 50-80 millimeters, and preferably of about 60-70 millimeters.

According to claim 1 0, one of the at least one end row may include more than one battery cell less than each of said at least two rows. Further, the end row may include a power transfer connector within the parallelogram shaped battery pack. By providing the power transfer connector inside the battery pack, the battery pack may be more compact. Further, a power transfer connector within the parallelogram shaped battery pack may be more protected than a power transfer connector provided outside the battery pack.

According to claim 1 1 , in another aspect of the invention, a battery powered tool may be provided including a battery pack according to any of the claims 1 -10. Moreover, according to claim 12, the battery powered tool may be a hand-held garden tool. 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 illustrates a perspective view of a chainsaw, according to an

embodiment of the present invention;

FIG. 2A illustrates a perspective view of a battery pack, according to an embodiment of the present invention; and

FIG. 2B illustrates a sectional view of the battery pack, 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 util ized in other embodiments and even other types of devices. In the drawings, like numbers refer to like elements.

FIG. 1 illustrates a partial perspective view of an example battery powered chainsaw 100, according to an embodiment of the present invention. The chainsaw 100 may be used in garden ing or forestry appl ications. However, the present invention may also be incorporated in any other battery powered tools, for example line trimmers, hedge trimmers, drills, reciprocating saws, rotary saws, power screw drivers, or other hand-held power or garden 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.

The chainsaw 100 includes a main body 102 which encloses a prime mover (not shown). In various other embodiments of the invention, the prime mover may be an electric motor, such as, but not limited to, an AC motor, a DC motor, or the like. The electric motor is selectively supplied with electrical energy by a battery pack 104. The activation or deactivation of the electric motor may be controlled by an on/off switch (not shown in FIG. 1). Further, the chainsaw includes other control means, which may include one or more sensors to regulate various parameters of the drive motor, for example speed, torque etc. The rated power and other specifications of the electric motor may be selected based on various parameters, for example power requirements, expected life, cost, weight or dimensions.

Further, the chainsaw 100 includes a working implement (not shown) coupled to the main body 102. Typically, the working implement includes a guide bar with a continuous peripheral guiding slot to support a saw chain. Further, 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 main body 102, such that the saw chain rides over them. During operation of the chainsaw 100, the drive sprocket and thus, the saw chain may be driven by the electric motor via suitable transmission means (not shown in the figures) which may include for example (but are 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 drive sprocket at one or more speeds.

As illustrated in FIG. 1 , the main body 102 also includes a top handle 106 and a side handle 108 (partially shown in FIG. 1). However, other types of handle configurations (for example a rear handle configuration) may be possible without departing from the scope of the present invention. The top handle 106 and/or the side handle 108 may include grip portions to aid in manual grasping of the chainsaw 100. Further, a guard 110 is provided to safeguard a user during a cutting operation.

FIG. 2A illustrates a perspective view of the battery pack 104, according to an embodiment of the present invention, with a cover removed. The battery pack 104 may be detachably attached to the main body 102 of the chainsaw 100 to aid in charging, maintenance and/or storage. The battery pack 104 may include suitable releasable mechanical connections (not shown in the figures), for example, but not limiting to, snap-fit connections, mating recesses and grooves, connections with resilient members (for example springs), or a combination of any of these to mechanically connect the battery pack 104 to the main body 102 of the chainsaw 100 without any special tools. However, in an alternative embodiment of the present invention, the battery pack 104 may be fixedly attached to the electric power tool 100.

As illustrated in FIG. 2A, the battery pack 104 includes a plurality of battery cells 202 (hereinafter referred to as "the cells 202") encased in a battery housing 204. Each of the cells 202 has a substantially cylindrical shape. However, any other shape of the cells 202 (for example cells with elliptic or rectangular cross-section) may be possible. Moreover, the cells 202 may be for example Lithium-Ion, Nickel-Cadmium, or the like based cells. The number and type of the cel ls 202 may be selected based on various parameters, such as, but not limited to, power and charge requirements, cost, weight and dimensions of the electric power tool 100.

As illustrated in FIG. 2A, the cells 202 are arranged in at least two rows 206 with at least two cells 202 in each of the rows 206. Further, the battery pack 104 also includes at least one end row 208 or 210 provided as the last row of the cells 202 on top and/or below of the rows 206. It may be noted that the positional terms "top" and "below" are used with respect to the orientation of the battery pack 104 as depicted in FIG. 2A. Further, the end row 208 includes at least one cell 202 less than each of the rows 206. Moreover, at least one of the end rows 208 and/or 210 may include more than one cell 202 less than each of the rows 206. By way of an example only, as illustrated in FIG. 2A, each of the rows 206 includes four cells 206. Moreover, the end row 208 provided at the top of the rows 206 includes three cells 206 while the end row 210 provided below the rows 206 includes one cell 202. The number of cells 202 and the number of rows 206, as illustrated in FIG. 2A, are for illustrative purposes only, and the battery pack 104 may include any number of cells 202 arranged in any number of rows 206 within the scope of the present invention. In various alternative embodiments of the present invention, two or more cells 202 may also be arranged adjacent to one another in a direction substantially perpendicular to the plane of the paper. Further, each of the rows 206, and/or end rows 208 and 210 are displaced relative to the closest row such that the battery pack 104 has a substantially parallelogram shaped cross-section (described in detail in conjunction with FIG. 2B). The parallelogram shaped cross-section of the battery pack 104 may lead to a compact arrangement of the cells 202. Such a compact configuration of the battery pack 104 may improve the handling and the ergonomics of the chainsaw 100. Further, the end rows 208 and/or 210 are provided with at least one cell 202 less than each of the rows 206 to result in a more compact configuration of the battery pack 104 (explained later in conjunction with FIG. 2B).

FIG. 2B illustrates a sectional view of the battery 104, according to an embodiment of the present invention. As illustrated in FIG. 2B each of the cells 202 has a diameter D. Further, each of the rows 206, and the end rows 208 and 210 are displaced relative to the closest row by substantially a distance equal to about half of the diameter D of a cell 202, i.e. D/2. This results to a substantially parallelogram shaped cross-section of the battery pack 104. Further, the relative displacement by the distance equal to about D/2 provides an optimum arrangement of the cells 202, i .e. a maximum number of cells 202 can be accommodated in a given volume of the battery pack 104. Consequently, an output power of the battery pack 104 may be maximized for a given volume or size of the battery pack 104.

In an embodiment of the present invention, the diameter D of a cell 202 is substantially in a range from about 10 millimeters to about 25 millimeters, and preferably in a range of about 15 millimeters to about 20 millimeters, and more preferably of about 18 millimeters. Additionally, in an embodiment of the present invention, a length of each of the cells 202 is substantially in a range from about 50 millimeters to about 80 millimeters, and preferably in a range from about 60 millimeters to about 70 millimeters. It may be apparent to a person skilled in the art that the dimensions of the cells 202 are purely exemplary in nature and the cells 202 may have any other dimensions without departing from the essence of the present invention.

Further, as illustrated in FIG. 2B, two sides 212 and 216 of the battery housing 204 are substantially parallel to each other and two sides 214 and 218 of the battery housing 204 are substantially parallel to each other. As illustrated in FIG. 2B, the two sides 212 and 214 of the battery housing 204 form an angle a between them. Moreover, an angle between the sides 216 and 218 is substantially equal to the angle a due to the parallelogram shaped cross-section of the battery pack 104. In an embodiment of the present invention, the angle a may lie substantially in a range from about 30 degrees to 80 degrees, and preferably from about 50 degrees to 70 degrees. Further, as illustrated in FIG. 2B, the two sides 212 and 218 of the battery housing 204 form an angle β between them. Moreover, an angle between the sides 214 and 216 is substantially equal to the angle β due to the parallelogram shaped cross-section of the battery pack 104. In an embodiment of the present invention, the angle β is substantially in a range from about 100 degrees to 150 degrees, and preferably in a range from about 1 10 degrees to 130 degrees. The ranges of the angles a and β may result in a more compact configuration of the battery pack 104. However, it may be apparent to a person skilled in the art that the ranges of the angles a and β are purely exemplary in nature and the angles a and β may have any values without departing from the essence of the present invention. Moreover, the sides 212, 214, 216 and 218 of the battery housing 204 may be of any length or thickness.

Further, the cells 202 in the end row 208 are arranged such that the parallelogram shaped cross-section of the battery pack 104 is provided with a first truncated corner 220 between the sides 212 and 214 of the battery housing 204. By way of an example, the end row 208 has at least one cell 202 less than each of the rows 206 to enable the formation of the first truncated corner 220. Further, the cells 202 in the end row 210 are arranged such that the parallelogram shaped cross-section of the battery pack 104 is provided with a second truncated corner 222 between the sides 216 and 218. By way of an example, the end row 210 has at least one cell 202 less than each of the rows 206 to result in the formation of the second truncated corner 222. The first truncated corner 220 and/or the second truncated corner 222 may result in an even more compact configuration of the battery pack 104 by removing at least one sharp corner from the parallelogram shaped cross- section of the battery pack 104.

As illustrated in FIG. 2B, the end row 210 may include a power transfer connector 224 which is situated within the battery housing 204. By way of an example, the power transfer connector 224 is accommodated within the battery housing 204 by providing the end row 210 with at least two cells 202 less than each of the rows 206. The power transfer connector 224 may include one or more terminals made of an electrically conducting material. The power transfer connector 224 may electrically connect the cells 202 to one or more tool electric terminals (not shown in the figures) provided on the main body 102 of the chainsaw 100. Further, the battery pack 104 may include one or more electrical conductors (not shown in the figures) to electrically connect poles of the cells 202 to the power transfer connector 224. Moreover, the power transfer connector 224 may also be utilized to charge the cells 202 from an external power source. By providing the power transfer connector 224 inside the battery housing 204, instead of mounting the power transfer connector 224 on an outer surface of the battery housing 204, the battery pack 104 may be more compact. Additionally, the power transfer connector 224 may be safeguarded from corrosive elements (For example, moisture) and mechanical damage during handling.

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.

Claims

1 . A battery pack (104) for a battery powered tool (100), wherein the battery pack (104) comprises; a plurality of battery cells (202) provided in at least two rows (206) with at least two battery cells (202) in each row (206), wherein the rows (206) are placed on top of each other and wherein each row (206) is displaced relative to each closest row, such that a parallelogram shaped cross-section of the battery pack (104) is formed,

characterized in that the battery pack (104) further comprises at least one end row (208, 210) provided as the last row of battery cells on top or below said at least two rows (206), which at least one end row (208, 210) comprises at least one battery cell (202) less than each of said at least two rows (206).

2. The battery pack (104) according to claim 1 , wherein the battery cell/s (202) in the at least one end row (208, 210)) is located such that the parallelogram shape is provided with a truncated corner (220, 222).

3. The battery pack (104) according to claim 1 or 2, wherein the battery cells (202) are cylindrically shaped.

4. The battery pack (104) according to claim 3, wherein the rows (206, 208, 210) are displaced relative to each closest row by a distance of half the diameter (D) of a battery cell (202).

5. The battery pack (104) according to any of the preceding claims, wherein two sides (212, 218) of the parallelogram shaped battery pack (104) forms an angle (β) of about 100-150 degrees, and preferably of about 1 10- 130 degrees.

6. The battery pack (104) according to any of the preceding claims, wherein two sides (212, 214) of the parallelogram shaped battery pack forms an angle (a) of about 30-80 degrees, and preferably of about 50-70 degrees.

7. The battery pack (104) according to any of the claims 2-6, wherein two corners (220, 222) of the parallelogram shaped battery pack (104) are truncated.

8. The battery pack (104) according to claim 3, wherein the diameter (D) of a battery cell (202) is in the range of about 10-25 millimeters, preferably of about 15-20 millimeters, and more preferably of about 18 millimeters.

9. The battery pack (104) according to any of the preceding claims, wherein the battery cells (202) have a length in the range of about 50-80 millimeters, and preferably of about 60-70 millimeters.

10. The battery pack (104) according to any of the preceding claims, wherein one of the at least one end row (210) comprises more than one battery cell less than each of said at least two rows (206), wherein the end row (210) comprises a power transfer connector (224) within the

parallelogram shaped battery pack (104).

1 1 . A battery powered tool (100) comprising the battery pack (104) according to any of the claims 1 -10.

12. The battery powered tool (100) according to claim 1 1 , wherein the battery powered tool (100) is a hand-held garden tool.