WO2019061088A1

WO2019061088A1 - Plate for cooling a power tool

Info

Publication number: WO2019061088A1
Application number: PCT/CN2017/103734
Authority: WO
Inventors: Eric Lennings
Original assignee: Changzhou Globe Co Ltd
Current assignee: Changzhou Globe Co Ltd
Priority date: 2017-09-27
Filing date: 2017-09-27
Publication date: 2019-04-04
Anticipated expiration: 2020-03-27
Also published as: CN107570799A; CN107570799B; CN207521809U

Abstract

Un outil électrique comprend un boîtier non métallique (20) comprenant un moteur électrique (22) et une batterie (24). Le moteur électrique (24) est commandé par un dispositif de commande disposé sur une carte de Circuit imprimé, PCB, (10), une surface de la PCB (10) étant en contact avec une plaque de refroidissement métallique (2) agencée sur un côté inférieur (21) du boîtier non métallique (20).A power tool includes a non-metallic housing (20) including an electric motor (22) and a battery (24). The electric motor (24) is controlled by a control device disposed on a printed circuit board, PCB, (10), a surface of the PCB (10) being in contact with a metal cooling plate (2) arranged on a lower side (21) of the nonmetallic housing (20).

Description

PLATE FOR COOLING A POWER TOOL

Technical field

The present invention relates generally to power tools and more specific to cooling of power tools, such as chainsaws, trimmers, blowers, hedge trimmers and the like.

Background art

During the last decades, power tools have become more and more popular due to the development of more efficient batteries. One advantage with power tools is the possibility to readily control the performance of an electrical motor provided in a housing of the power tool. The electrical motor is controlled by a controller or control unit, the components thereof being provided on a Printed Circuit Board, PCB. A problem with the controller and PCB is that they generate heat. Thus, there is a need for cooling the electrical components of the power tool.

Traditionally, cooling in power tools is provided by incorporating turbines and/or ventilators inside the housing of the power tool, which create an air circulation around the controller and the PCB. However, the introduction of turbines and ventilators increase the complexity and cost of the power tools. Turbines and ventilators also require energy, which will drain the scarce power resource of the batteries used for power tools.

Another solution to the cooling problem is disclosed in EP 1 961 528, which primarily is directed to the cooling of the electrical motor, but also to cooling of components on an electronic control card. In EP 1 961 528 the electrical motor is enclosed by a housing made of light metal alloy. The housing comprises at least two parts. The electrical motor is in contact with the surface of the housing in order to provide static cooling of a power toll in form of a power tool. To further increase the cooling efficiency the housing may be provided with cooling fins.

There are at least two problems with having an all metallic housing, even if it is a light metal alloy. Firstly, the weight of the housing and thus the power tool increases compared to a plastic housing. This makes the power tool more difficult to handle and in the end, it might make the operator more fatigue and will in that sense be a safety issue. Secondly, since the metallic housing is a good heat conductor heat will spread to the entire housing. This heat may make the operator warm or hot and in some cases the operator might also burn himself on the housing. Everyone that has touched a hot surface knows that this can cause sudden movements away from the heat, which could be very dangerous if you are holding a power tool in your hands.

Thus, there is a need to find an efficient way to preform cooling of a power tool, which does not jeopardize the safety of an operator and which is simple and does not require any additional power from the battery.

Summary of invention

An object of the present invention is to accomplish a power tool having efficient cooling, while at the same time keeping the complexity of the power tool as low as possible.

According to one aspect this is accomplished by a power tool comprising a non-metallic housing comprising an electrical motor and a battery. The electrical motor is controlled by a controller provided on a Printed Circuit Board, PCB, wherein a surface of the PCB is in contact with a metallic cooling plate arranged on a bottom side of the non-metallic housing.

In an embodiment of the power tool, the metallic cooling plate is made of aluminium or alloys thereof.

In another embodiment of the power tool, the metallic cooling plate is made of magnesium or alloys thereof.

Furthermore, the metallic cooling plate may further comprise a cavity, the size of which is adapted to receive the PCB.

In yet another embodiment of the power tool, the metallic cooling plate is provided with vent holes. A part of these vent holes may be provided inside the cavity. In order to prevent dust the vent holes may furthermore be covered by or provided with a filter on a side of the metallic cooling plate that is directed to the inside of the housing.

Preferably, the housing of the power tool is made of plastic.

By providing a metallic bottom plate at the bottom side of the non-metallic housing of the power tool in contact with the PCB, cooling of the PCB and its components is provided without leading heat to the parts of the housing that might be in contact with an operator. This solution will thus not affect the safety as the solution according to the cited prior art. Furthermore, the use of a cooling plate eliminates the need to use turbines and ventilators to cool the power tool. In this way, a simple solution to the problem has been achieved without substantially affecting the weight of the power tool.

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 side view of a power tool, exemplified as a chainsaw, according to an embodiment.

Fig. 2 is perspective view looking at the bottom side of the power tool.

Fig. 3 is a metallic cooling plate according to an embodiment.

Fig. 4 is a metallic cooling plate according to an embodiment.

Fig. 5 is a metallic cooling plate according to an embodiment.

Fig. 6 is a schematic view of a printed circuit board and its components.

Description of embodiments

In the following, a detailed description of the cooling plate of the power tool will be presented.

With reference to Fig. 1 a schematic side view of a power tool according to an embodiment of the present invention is shown. It should be understood that even if Fig. 1 exemplifies the power tool with an electrical chainsaw, the present invention is not limited to this. An electrical chainsaw is merely an example of a power tool. Other examples are trimmers, blowers, hedge trimmers etc. The electrical chainsaw tool comprises a cutting chain 28 that is rotatably mounted on a chain guide 26. In other embodiments, the cutting chain is substituted by other tools. When operated the cutting chain 28 is rotated by means of a drive pinion. The drive pinion is driven by an electrical motor 22, which is powered by a battery 24. The output of the electrical motor 22 is controlled by a controller provided on a Printed Circuit Board, PCB 10. Some of the components 12 of the controller are schematically depicted in the Fig. 1. The electrical motor 22, the battery 24, the PCB 10 and the components provided thereon are all enclosed by a housing 20. The housing 20 is made of a non-metallic material preferably plastic or composite or the like. The aim of the present invention is to provide cooling for the PCB 10 and all the components 12 thereon. Thus, the described housing 20 is representative for a general housing of a power tool.

Turning now to Fig. 2 a perspective view of the power tool is shown, looking at the bottom side 21 of the power tool. The same reference numerals denote the same objects as in Fig. 1. They are therefore not repeated here once again. Not previously shown in Fig. 1, but now shown in Fig. 2 is a metallic cooling plate 2. It is the metallic cooling plate 2 that is used to cool the PCB 10 and its components 12. Different embodiments of the cooling plate 2 are shown in more detail in Figs. 3 to 5. A more detailed view of the PCB 10 and its components 12 is shown in Fig. 6.

Turning now to Fig. 3, the cooling plate 2 will be described in more detail. In Fig. 3 to Fig. 5 the cooling plate 2 is essentially square-shaped. However, these shapes are only examples of how a cooling plate 2 may be configured. The important thing is that the shape of the cooling plate 2 is adapted to the bottom side 21 of the housing 20 and to the PCB 10, which it is cooling.

In Fig. 3 the cooling plate 2 comprises a cavity 4, the size and depth of which is adapted to receive the PCB 10. The cooling plate 2 and/or the cavity 4 may furthermore also be adapted to receive or be in direct contact with some of the components 12. This may provide more cooling effect directly to a specific component 12 if it is desired. For example, a processer may be provided with a cooling flange that is in direct contact with the cooling plate 2.

The cooling plate 2 may furthermore be provided with vent holes 26, which allows that air from the outside reaches inside the housing 20 and cools the PCB 10. The vent holes may be designed in numerous different way when it comes to size, number and where on the cooling plate 2 they are provided. Different examples of vent hole 6 configurations are shown throughout Fig. 3 to Fig. 5. For example, in Fig. 5 a part of the vent holes 6 are provided in the cavity 4. It is believed to be within the capability of a person skilled in the art to design the size, number and place of the vent holes 6.

Furthermore, in some embodiments the vent holes 6 may be covered by a filter on a side of the metallic cooling plate 2 that is directed towards the inside of the housing 20. The filter is used to prevent dust and other particles to enter into the housing 20 of the power tool.

The cooling plate 2 may also comprise through holes 8, which are used to fasten the cooling plate 2 to the bottom side 21 of the housing 20. The number of through holes 8 is, as recognized by a person skilled in the art, adapted to the geometry of the cooling plate 2 and the geometry of the bottom side 2 of the housing 20. Different examples of through holes 8, and placement thereof are shown throughout the Figs.

As mentioned above the cooling plate 2 is made of metal. In one embodiment, the cooling plate 2 is made of aluminium or alloys thereof. In another embodiment, the cooling plate 2 is made of magnesium or alloys thereof. When choosing the type of metal to be used as cooling plate 2, it is important to bear in mind the cooling effect of the metal and the weight of the metal. It is important that the cooling plate 2 does not add to much weight to the overall weight of the power tool.

Turning now to Fig. 6 a more detailed view of the PCB 10 and its components 12 are shown. The components 12 constitute different parts of a controller, such as a processor, a memory etc. that are used to control the electrical motor 22.

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 power tool comprising a non-metallic housing (20) comprising an electrical motor (22) and a battery (24) , said electrical motor (24) being controlled by a controller provided on a Printed Circuit Board, PCB, (10) , wherein a surface of the PCB (10) is in contact with a metallic cooling plate (2) arranged on a bottom side (21) of the non-metallic housing (20) .
The power tool according to claim 1, wherein the metallic cooling plate is made of aluminium or alloys thereof.
The power tool according to claim 1, wherein the metallic cooling plate is made of magnesium or alloys thereof.
The power tool according to any of the previous claims, wherein the metallic cooling plate (2) further comprises a cavity (4) , the size of which is adapted to receive the PCB (10) .
The power tool according to any of the previous claims, wherein the metallic cooling plate (2) is provided with vent holes (6) .
The power tool according to claim 5, wherein a part of the vent holes (6) are provided in the cavity (4) .
The power tool according to any of the previous claims, wherein the vent holes (6) are covered by a filter on a side of the metallic cooling plate (2) that is directed towards the inside of the non-metallic housing (20) .
The power tool according to any of the previous claims, wherein the non-metallic housing is made of plastic.