HK1137695B - Static cooling electric chain saw and method used to achieve said cooling - Google Patents

Description

Statically cooled electric chain saw and method for achieving said cooling

Technical Field

The invention relates to an electric chain saw with static cooling and a method for achieving the same.

More particularly, the present invention relates to a chain saw in which driving of a cutting chain is achieved by an electric motor.

Background

The driving of the cutting chain of the known electric chainsaw is achieved by an electric motor of low efficiency, so that about 50% of the power delivered by the motor is dissipated to avoid the effect of overheating, due to the large heat losses that occur.

The equipment for performing the dissipation of the heat generated by the electric motor is a turbine or a fan generating an air circulation around the motor. The addition of a turbine or fan to the motor of the saw makes the manufacture of the tool inconvenient, increases its cost, and results in the consumption of additional energy in addition to that required to drive the cutting chain.

Furthermore, to improve efficiency, this cooling system requires the provision of openings in the housing of the motor to facilitate the circulation of cooling air around the housing. The main inconvenience of these openings is to break the tightness of the motor and to allow water, dust and sawdust from cutting the wood to enter therein.

Document US-2005/0236917 describes an electric hand tool comprising an electric motor enclosed in a cover in turn housed in a housing of the tool, and a cooling system comprising heat conducting means connecting said cover and said housing in order to dissipate the heat generated by the motor. Such cooling devices complicate the manufacture of the tool and do not allow efficient heat dissipation for high power electric motors, such as those typically provided with electric chain saws.

Disclosure of Invention

The main object of the present invention is to eliminate the above mentioned inconveniences of an electric chain saw and its cooling system.

Chain saws, commonly known as cutters, are common and are commonly used to cut a variety of materials (wood, concrete, brick, square slate, etc.). It comprises a cutting device constituted by an endless (uninterrupted, end-to-end) cutting chain mounted to rotate around a transmission (drive) pinion (sprocket) and a chain guide that is oblong in its entirety and provided with peripheral guide rails, and a power source comprising, in the case of an electric saw, an electric motor that drives the chain through said pinion.

According to a first characteristic arrangement of the invention, the electric motor driving the cutting chain comprises a brushless direct current motor, commonly known as "brushless" motor, which is enclosed in a casing comprising at least two parts and made of light metal alloy, one surface of which is in contact with the motor to ensure static cooling of said motor.

According to another characteristic arrangement, the chainsaw comprises a control circuit board of the motor driving the cutting chain, also housed in said cooling housing, the surface of which is in direct contact with the switching part of this control circuit board.

Preferably, the cooling housing is made of an aluminum alloy or a magnesium alloy.

According to a preferred embodiment, at least one component of the housing comprises one or more heat sinks.

According to another embodiment, one of the surfaces of one of the components of the cooling housing is fitted as a removable chain guide for receiving and supporting the tool, the surface being in contact with the chain guide such that the chain guide assists in dissipating heat generated by the motor.

According to another embodiment, a chainsaw handle attached to a cooling housing of the chainsaw forms a (heat) exchanger arrangement that participates in cooling a motor driving a cutting chain of the chainsaw.

Preferably, the handle is an integral part of the housing.

According to another embodiment, the cooling handle is fixed to the two parts forming the housing.

According to another embodiment applied to a chainsaw with a bar, the bar also forms an exchanger device that participates in cooling the motor that drives the cutting chain of the saw.

Advantageously, the various components of the cooling housing, the chain guide, the handle and the lever cooperate with the motor and with the control circuit board of the motor to transfer heat generated by the motor and by the control circuit board of the motor to the outside.

According to an advantageous embodiment, the stator of the motor is in direct contact with one of the parts of the cooling housing.

Advantageously, the lead-out wires of the windings of the stator of the motor are surrounded by one or the other part of the housing and do not touch.

Advantageously, the housing in which the motor and the control circuit board are housed respectively is separated by a cooling partition arranged in the two parts of the cooling housing.

Advantageously, the assembly of the two parts of the housing is waterproof and dust-proof.

The static cooling of the electric chain saw according to the invention has several advantageous advantages:

the use of a brushless motor with an efficiency above 68% and producing little heat loss, i.e. little energy consumption, enables the formation of an efficient means for static cooling by convection or radiation. The device also allows the release of heat released by the power switch components of the control circuit board.

The better efficiency of the motor and the static cooling means make the body of the tool small and light, which does not make the use of the tool inconvenient.

The cooling device is economical and simple in design without adding any additional parts exclusively to the motor.

There is no need to preset any opening in the housing, so that water, dust and sawdust can be prevented.

The motor-and cooling system equipped electric chain saw according to the invention constitutes a professional tool that can work for a long time.

According to the method of the invention, the driving of the chain is effected by a brushless direct current motor, and this motor is housed in a casing comprising at least two parts and made of a light metal alloy, at least one surface of the casing being placed in contact with the motor so as to ensure static cooling of the motor.

According to a preferred mode of operation of the electric saw applied to a control circuit board comprising a motor, the method is further characterized in that the switching part of said control circuit board is placed in contact with a surface of at least one part of the cooling housing.

Drawings

The objects, features, advantages, etc. of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a front view of an embodiment of a chain saw used in the present invention;

FIG. 2 is a cross-sectional view, partially broken away and cut away, taken along line II-II of FIG. 1;

FIG. 3 is a view similar to FIG. 2 showing a chainsaw according to a second embodiment of the present invention;

fig. 4 is also a view similar to fig. 2, showing a chain saw according to a third embodiment of the present invention.

Detailed Description

The advantageous examples described in connection with the figures do not limit the chainsaw and the cooling method according to the invention.

The functionally identical components of the chain saw in the three embodiments shown and described are denoted by the same reference numerals in the figures and in the following description.

A chainsaw 1, which is commonly used for cutting various materials (wood, concrete, bricks, square slabs, etc.), comprises a cutting device, which is constituted by an endless chain 2 mounted to rotate around a drive pinion and an overall oblong chain guide 3, and a power source, which in this example is constituted by an electric motor 4.

According to the invention, the electric motor 4 is constituted by a high-efficiency brushless direct current machine with a power of more than 500W and an efficiency of more than 68%, for example with a power of about 1kW and an efficiency of about 85% to 90%, the operation of which generates only a small amount of thermal energy that needs to be dissipated.

The brushless motor 4 is accommodated in a housing 5 comprising at least two parts 5A, 5B and made of a light metal alloy with good heat conductivity, such as an aluminum alloy or a magnesium alloy.

The motor 4 is arranged in the casing 5 so as to be in direct contact with one of the surfaces of at least one (5A) of the parts 5A, 5B of the casing 5, thus ensuring static cooling of said motor by convection and/or radiation.

In certain preferred embodiments, the chainsaw may include a control circuit board 6 for the motor 4.

According to one embodiment, the control circuit board of the motor 4 for driving the cutting chain 2 of the chainsaw is also housed in the cooling housing 5, so that the electric switching member 6a is in contact with one of the surfaces of at least one of the parts 5A, 5B of the housing, thus ensuring static cooling of said switching member by convection and/or radiation.

The motor 4 is mounted in a first housing 7 in the housing 5, while the circuit board 6 is positioned in a second housing 8 which is arranged in the vicinity of the first housing and is separated from it by a partition 9 forming a cooling wall.

At least one of the parts 5A, 5B of the housing 5, preferably the part 5A as shown in the drawings, is provided with one or more outwardly extending cooling fins 10 which are substantially parallel and extend over the entire length of the housing 5, as shown in particular in fig. 1.

The stator 4a of the motor 4 is placed in direct contact with one (5A) of the parts 5A, 5B of the housing.

For example, the motor 4 is mounted in a cylindrical blind hole 13 providing the inner surface of the part 5A of the housing 5, the bottom 13' of which is in contact with the heat sink 10. Preferably, the stator 4a of the motor 4 directly contacts the side wall of the cylindrical blind hole 13.

On the other hand, the lead-out wires 4B of the windings of the stator 4a of the motor 4 are respectively enclosed by one or the other of the components 5A, 5B of the cooling case 5.

The two parts 5A, 5B of the housing 5 are assembled in a sealed manner by means of any suitable connection system (screws, bolts, etc.).

According to a further characteristic arrangement, one of the surfaces (5B') of one of the constituent parts 5A, 5B of the cooling housing 5 is arranged to receive and support a detachable metal chain guide of the chainsaw. In this case, the chain guide is in contact with the surface 5B' of the housing, so that said chain guide forms an additional heat exchange means and also helps to dissipate the heat generated by the motor 4 driving the cutting chain 2. The chain guide is made of a light metal alloy having good heat conductivity.

According to another embodiment, the handle of the chainsaw attached to the cooling housing 5 also forms an additional heat exchanger device that participates in dissipating the heat generated by the cutting chain of the motor 4 driven saw.

The handle may be an integral part of the housing 5. It may be attached to the cooling housing and fixed to one or both of the two parts 5A, 5B of the housing by any suitable means. In this case, the handle is made of a light metal alloy having good heat conductivity.

According to another embodiment of the chainsaw with a bar, the cutting head of which is arranged at a distance from the steering handle by means of an arm or bar 12, this bar also forms the heat exchange means that participates in the cooling of the motor 4 driving the cutting chain. In this case, the rod 12 and its connecting sleeve 11 are made of a light metal alloy with good thermal conductivity.

Each part 5A, 5B of the cooling housing 5, the removable chain guide 3, the handle and-in the case of a cutting machine with a lever-the lever 12 cooperates with the motor 4 and with the control circuit board 6 of said motor to transfer the heat generated by the motor and by the control circuit board to the outside.

According to the embodiment shown in fig. 3, the cylindrical portion 13 is open and the part 5A of the casing 5 comprises an opening 14 which allows access to the housing 7 and facilitates the placement or removal of the motor 4 in or from said housing 7. A metal cover 15 closes the opening 14, thereby forming the bottom of the cylindrical portion 13. The cover 15 comprises an annular skirt 15a which is forcibly engaged in the housing 7 and which brings a portion of the motor 4 against the cylindrical portion 13. The cover 15 is preferably made of the same heat transfer material as the material of which the other parts of the housing 5 are made.

According to the embodiment shown in fig. 4, the cooling housing 5 is limited to a single accommodation 16. The closure 15 is screwed onto a flange 17 of the housing 5. This flange 17 and the peripheral portion 15b of the cover 15 form a single blade 10 for the part 5A of the casing 5.

Claims (16)

1. An electric chainsaw comprising a cutting chain (2) mounted to rotate around a drive pinion and an oblong chain guide (3), and an electric motor (4) driving the chain through said pinion, consisting of a brushless direct current motor (4), characterized in that it is enclosed in a housing (5) made of a light metal alloy with good heat conduction properties and comprising at least two parts (5A, 5B), said electric motor (4) being in contact with the surface of said housing (5) in order to ensure static cooling of said motor, wherein one (5B') of the surfaces of one (5B) of said parts (5A, 5B) forming the housing (5) is arranged to receive and support the oblong chain guide (3) of the chainsaw, which is a removable metal chain guide, the surface is in contact with the metal chain guide such that the chain guide (3) assists in dissipating heat generated by the motor (4).

2. An electric chain saw according to claim 1, comprising a control circuit board (6) for driving the motor (4) for cutting the chain, characterized in that the circuit board (6) is also accommodated in said housing (5A, 5B), the surface of which is in direct contact with the switch part (6a) of the control circuit board.

3. The electric chain saw according to claim 1 or 2, wherein the housing (5A, 5B) is made of an aluminum alloy or a magnesium alloy.

4. The electric chain saw according to claim 1 or 2, characterized in that at least one (5A) of the parts (5A, 5B) of the housing (5) comprises one or more heat sinks (10).

5. An electric chainsaw according to claim 1 or 2, wherein the metal handle attached to the housing (5) of the chainsaw forms an additional exchanger device that participates in cooling the motor (4) driving the cutting chain (2) of the chainsaw.

6. An electric chain saw according to claim 5, wherein the handle is an integral part of the housing (5).

7. An electric chain saw according to claim 5, characterised in that the handle is fixed to the two component parts (5A, 5B) of the housing (5).

8. Electric chainsaw, according to claim 1 or 2, applied to a cutter with a bar, characterized in that the bar (12) also forms an exchanger device that participates in cooling the motor (4) driving the cutting chain (2) of the chainsaw.

9. The electric chain saw according to claim 8, characterized in that the various parts (5A, 5B) of the housing (5), the detachable chain guide (3), the handle and the lever (12) cooperate with the motor (4) and with the control circuit board (6) of the motor to transfer heat generated by the motor and the control circuit board of the motor to the outside.

10. The electric chain saw according to claim 1 or 2, characterized in that the stator (4a) of the motor (4) is in direct contact with one of the parts (5A) of the housing.

11. The electric chain saw according to claim 10, characterized in that the stator (4a) of the motor (4) is in direct contact with a side wall of a cylindrical portion (13) comprised in the housing, in which cylindrical portion the motor is housed, the side wall of which cylindrical portion being one of the parts of the housing.

12. The electric chain saw according to claim 1 or 2, characterized in that the lead-out wires (4B) of the windings of the stator (4a) of the motor (4) are closed by one part (5A) or the other part (5B) of the housing, respectively.

13. The electric chain saw according to claim 2, characterized in that the accommodation parts (7, 8) arranged in the parts (5A, 5B) of the housing (5) that accommodate the motor (4) and the control circuit board (6), respectively, are separated by a cooling partition (9) arranged in both parts of the housing.

14. The electric chain saw according to claim 2, characterized in that the two parts (5A, 5B) of the housing (5) are assembled in a sealed manner.

15. Method for static cooling of an electric chainsaw comprising a cutting chain (2) mounted for rotation around a drive pinion and an oblong chain guide (3), and an electric motor driving the chain through said pinion, the electric motor being constituted by a brushless direct current motor, characterized in that the electric motor is enclosed in a housing (5) made of a light metal alloy with good heat conduction properties and comprising at least two parts (5A, 5B), the electric motor (4) being placed in contact with at least one surface of the housing (5) to ensure static cooling of the motor, wherein one (5B') of the surfaces of one (5B) of the parts (5A, 5B) forming the housing (5) is arranged to receive and support the oblong chain guide (3) of the chainsaw, the oblong chain guide is a removable metal chain guide with which the surface is in contact so that the chain guide (3) assists in dissipating heat generated by the motor (4).

16. A method of statically cooling an electric chain saw according to claim 15, applied to a chain saw having a control circuit board (6) driving a motor (4) thereof for cutting the chain (2), characterized in that the switch part (6a) of the control circuit board (6) is placed in contact with a surface of at least one of the parts (5A, 5b) of the housing (5).