WO2019061089A1

WO2019061089A1 - Battery for power tools

Info

Publication number: WO2019061089A1
Application number: PCT/CN2017/103735
Authority: WO
Inventors: Eric Lennings; Ola Agne
Original assignee: Changzhou Globe Co., Ltd.
Priority date: 2017-09-27
Filing date: 2017-09-27
Publication date: 2019-04-04
Also published as: CN107689431A; CN207542283U

Abstract

The present invention relates to a battery (100) for power tools comprising a sealed casing (2), i.e. a casing (2) without any vents or other openings. The sealed casing (2) encloses a plurality of battery cells (6). An upper side (8) of the battery (100) is made of a metal part (4), i.e. the side of the battery (100) that extends outside a battery compartment (10) of a power tool when the battery (100) is inserted in the battery compartment (10). The metal part (4) is arranged to cool the battery cells (6) through conductive cooling.

Description

BATTERY FOR POWER TOOLS

Technical field

The present invention relates generally to batteries that are used for power tools, such as chainsaws, trimmers, hedge trimmers and the like. Especially, the present invention relates to a sealed battery for outdoor use.

Background art

During the last decades, battery-driven power tools such as chainsaws, trimmers, hedge trimmers, etc. have become more and more popular due to the development of more efficient batteries. More efficient and powerful batteries also require more efficient cooling.

A battery generally comprises a casing that encloses a number of battery cells that produce power. During this process heat is generated that needs to be cooled off to ensure proper functioning of the battery cells. One way to solve this problem according to prior art is to provide vents in the casing through which air can flow and cool down the battery cells. In order to further increase the cooling effect, it is known to use fans that create a higher flow of air and thereby a higher cooling effect. However, the use of fans and other means for increasing the air flow past the battery cells increases the complexity and cost for the battery.

However, under some circumstance the use of vents or other openings in the casing is disadvantageous. This is typically true when it comes to power tools for outdoor use or for use in harsh environments. For example, dirt, water and other objects may enter through the vents and openings in the casing and reduce the useful life of the battery. Water may also potentially be hazardous as it may short-circuit the battery. Thus, in this aspect it would be great to seal all vents and openings, with the disadvantage of overheating the battery.

Thus, there is a need for a battery that is sealed, but without the risk of getting overheated. There is also a need for a battery that is simple to manufacture without any means, such as fans, that increase the complexity of the battery.

Summary of invention

An object of the present invention is to accomplish a battery for power tools that is sealed and yet is able to cool the battery without overheating.

According to one aspect of the present invention this is accomplished by a battery for power tools that comprises a sealed casing, i.e. a casing without any vents or other openings. The sealed casing encloses a plurality of battery cells. An upper side of the battery is made of a metal part, i.e. the side of the battery that extends outside a battery compartment of a power tool when the battery is inserted in the battery compartment. The metal part is arranged such that it cools the battery cells through conductive cooling.

In one embodiment, the metal plate is made of aluminium or alloys thereof. In another embodiment, the metal part is made of magnesium or alloys thereof.

In yet another embodiment the metal part is essentially plate shaped and is arranged such that it seals the casing at the upper side of the battery.

Preferably, the metal part constitutes 3 to 15％of the length of the battery.

In another embodiment, the metal part may be essentially T-shaped and arranged such that the top of the T seals the casing at the upper side of the battery and the bottom of the T extends inwards into the interior of the casing. The bottom of the T may further comprise extensions, running parallel with the top of the T and extending into the interior of the casing in between the battery cells.

Thus, according to the present invention it is possible to accomplish a sealed battery, such that it may be IP classified as dust and waterproof, and also achieve good cooling of the battery without the need for any vents in the casing. Another advantage with the battery according to the present invention is that it may be charged without using a fan for cooling.

Brief description of drawings

The invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Fig. 1 is a schematic perspective view of a battery for power tools.

Fig. 2 is a cross sectional view of the battery along A-Ain Fig. 1.

Fig. 3 is a cross sectional view of the battery along A-Ain Fig. 1.

Fig. 4 is a cross sectional view of the battery along A-Ain Fig. 1.

Fig. 5 is a chainsaw, showing how a battery is inserted in a battery compartment thereof.

Description of embodiments

In the following, a detailed description of a battery according to embodiments of the present invention will be presented.

With reference to Fig. 1 a schematic perspective view of a battery for power tools is shown. As for most batteries used for power tools it has a general shape of a cuboid. However, the shape may be varied in many ways and what is important is that the battery matches a battery compartment provided somewhere on the power tool. In context of this application a power tool is a tool that is used primarily in the garden or sometimes also in the forest and is driven or powered by a battery. Examples of such power tools may be, mowers, robotic mowers, chainsaws, blowers, trimmers, hedge trimmers etc. Thus, the battery is primarily used outdoors and/or in harsh environments.

Returning now to Fig. 1, the battery is generally denoted with reference numeral 100. The battery 100 comprises a casing 2, which encloses a number of battery cells, which battery cells will be further described below in conjunction with Figs. 2 to 4. The casing 2 is preferably made of some type of plastic. The shape is as mentioned above generally cuboidal having a length L. The upper side of the battery 100 is made of a metal part 4, i.e. the side of the battery 100 that extends outside the battery compartment of the power tool when the battery 100 is inserted into the battery compartment, which is closer shown in Fig. 5. The metal part 4 seals the top (upper side) of the battery 100 and depending on the desired cooling capacity the thickness t may vary. In a preferred embodiment, the thickness t (see Fig. 4) of the metal part 4 is 3-15％of the length L of the battery 100.

One big difference with the battery 100 shown in Fig. 1 and prior art batteries is that there are no vents or other openings in the casing 2. Thus, according to the present invention the battery 100 cannot be cooled by circulating air through the casing 2. The reason for sealing the battery is to make the battery dust and waterproof such that it may be IP class approved.

Fig. 2 to Fig. 4 are all cross-sectional views of the battery along line A-A in Fig. 1. The difference between the different embodiments is the configuration of the metal part 4 and the number of battery cells, which are denoted with 6 throughout the figures.

In the cross-sectional view of Fig. 2, the upper side is denoted with 8. As further can be seen there are 16 battery cells 6 in this exemplary embodiment, only one of which has been denoted in order not to smudge the drawings. The number of battery cells 6 and how they are provided inside the casing 2 is not part of this invention as such and will therefore not be described in any more detail. Thus, the number, size and arrangement of battery cells 6 may vary considerable, but the cooling principle of the present invention will basically be applicable to all of them.

In the embodiment in Fig. 2 the metal part 4 is essentially plate shaped and arranged such that it seals the casing 2 at the upper side 8 of the battery 100. The metal part 4 may be seen as a lid that seals the casing 2. In order to secure a proper sealing there may be provided a gasket between the metal part 4 and the casing 2. The metal part 4 cools the battery by using conductive cooling. That is the metal part 4 conducts the heat away from the battery cells 6 and releases it to the ambient air at the upper side 8 of the battery.

The metal plate 4, is as the name indicates made of metal. The properties of the metal that are important is the weight of the metal and the heat conductivity of the metal. Metals that have proven to fulfill these properties are aluminium, magnesium and alloys thereof.

In Fig. 3 another embodiment of the metal part 4 is shown. Also in this embodiment, the metal plate 4 is essentially plate shaped at the upper side 8 of the battery 100, but has also an extension, extending inwards to the interior of the casing 2. Thus, in the cross-section of Fig. 3 the metal part 4 is essentially T-shaped and arranged such that the top of the T seals the casing 2 at the upper side 8 of the battery 100 and the bottom of the T extends inwards into the interior of the casing 2. By having an extra extension into the interior of the casing 2 closer to the battery cells 6 the cooling effect of the metal part 4 will increase further.

Turning now to Fig. 4 yet another embodiment of the metal plate 4 will be described having an even greater cooling capacity. The shape of this metal plate 4 is basically also T-shaped as the embodiment described in conjunction with Fig. 3. However, the bottom of the T further comprises extensions, running parallel with the top of the T and extending into the interior of the casing 2 in between the battery cells 6. Thus, there are many different shapes that are possible for the metal part 4, of which different shapes have been shown in this description. Thus, it is believed that a person skilled in the art and reading this description is capable of designing other shapes of the metal part 4 without deviating from the scope of the present disclosure.

Fig. 5 shows an example of a power tool, in this case a chainsaw, in which a battery 100 according to the present invention is inserted in a battery compartment 10 thereof. As can be seen the upper side 8 of the battery 100 comprises the metal part 4 which extends outside the battery compartment 10, such the metal part 4 can carry off the heat from the metal part 4 to the ambient air.

Although, the present invention has been described above with reference to specific embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the invention is limited only by the accompanying claims.

In the claims, the term “comprises/comprising” does not exclude the presence of other elements or steps. Furthermore, although individually listed, a plurality of means or elements may be implemented by e.g. a single unit or processor. Additionally, although individual features may be included in different claims, these may possibly advantageously be combined, and the inclusion in different claims does not imply that a combination of features is not feasible and/or advantageous. In addition, singular references do not exclude a plurality. The terms “a” , “an” , “first” , “second” etc do not preclude a plurality. Reference signs in the claims are provided merely as a clarifying example and shall not be construed as limiting the scope of the claims in any way.

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Claims

A battery (100) for power tools comprising a sealed casing (2) , i.e. a casing (2) without any vents or other openings, said sealed casing (2) enclosing a plurality of battery cells (6) , wherein an upper side (8) of the battery (100) is made of a metal part (4) , i.e. the side of the battery (100) that extends outside a battery compartment (10) of a power tool when the battery (100) is inserted in the battery compartment (10) , the metal part (4) being arranged to cool the battery cells (6) through conductive cooling.
The battery (100) according to claim 1, wherein the metal part (4) is made of aluminium or alloys thereof.
The battery (100) according to claim 1, wherein the metal part (4) is made of magnesium or alloys thereof.
The battery (100) according to any of the previous claims, wherein the metal part (4) is essentially plate shaped and is arranged such that it seals the casing (2) at the upper side (8) of the battery (100) .
The battery (100) according to any of the previous claims, wherein the thickness (t) of the metal part (4) constitutes 3 to 15％of the length (L) of the battery (100) .
The battery (100) according to any of claims 1 to 3, wherein the metal part (4) is essentially T-shaped and arranged such that the top of the T seals the casing (2) at the upper side (8) of the battery (100) and the bottom of the T extends inwards into the interior of the casing (2) .
The battery (100) according to claim 6, wherein the bottom of the T further comprises extensions, running parallel with the top of the T and extending into the interior of the casing (2) in between the battery cells (6) .