WO2012139508A1

WO2012139508A1 - Power tool and fan thereof

Info

Publication number: WO2012139508A1
Application number: PCT/CN2012/073909
Authority: WO
Inventors: Jizhong Fu
Original assignee: Bosch Power Tools (China) Co., Ltd.
Priority date: 2011-04-15
Filing date: 2012-04-12
Publication date: 2012-10-18
Also published as: JP5855226B2; JP2014516806A; DE112012001710T5; CN202001331U

Abstract

A fan for a power tool is provided, which comprises a fan body made of a plastic material and a metal disk attached to a front end of the fan body, wherein the metal disk comprises an annular disk body in the form of a flat plate, teeth, configured for speed detecting, extending outwards around a circumference of the annular disk body, and a braking surface formed by a front surface of the annular disk body. A power tool comprising the fan is also provided.

Description

POWER TOOL AND FAN THEREOF

Technical Field

The invention relates to a fan for a power tool as well as a power tool comprising such a fan.

Background Art

Power tools with cooling fan structures, such as circular saws, angle grinders, marble cutters and other power tools, are known in the art. It is desired for users to obtain some parameters of the power tools, such as speeds of rotation of their rotors. In addition, it is desired for users to stop the rotation of the power tools more efficiently in some applications.

Published patent application EP2138279 discloses a portable angle grinder provided with a mechanical braking system. The mechanical braking system comprises a metal disk, the metal disk being fixed on a shaft of a rotor in front of a fan and therefore rotating with the rotor, wherein the metal disk can act as a brake when it is required to stop the rotor, for example, through pressing a braking block against the metal disk by means of a mechanical force or an electromagnetic force or a force in other forms, which causes the tools to stop rotating in a much shorter time.

For some other power tools with fan structures, such as a Hitachi circular saw C6UVY, an additional metal disk is provided in front of a fan, the additional metal disk being configured for speed detection.

Another example of power tools with fan structures is a Makita circular saw 5732C, in which a sheet metal is molded into a plastic fan for speed detection.

All the power tools mentioned above have some drawbacks. Adding an additional metal disk in front of a fan increases the size of a tool, and therefore prolongs the assembling time. For the Makita circular saw 5732C, a metal disk is molded into a fan, the metal disk having only a single speed detection function, and thus the metal disk cannot be used for other functions, for example, braking function.

Therefore, it is desired to provide a fan to overcome the drawbacks mentioned above. Summary of the Invention

An object of the invention is to provide a fan for a power tool to overcome the drawbacks mentioned above and to provide a power tool comprising such a fan.

The drawbacks are overcome through providing special structural features on a surface of a metal disk so that a fan and the metal disk are molded into an integral piece, which makes it possible that the fan has functions of speed detection and mechanical braking simultaneously.

In one aspect of the invention, a fan for a power tool is provided, which comprises a fan body made of a plastic material and a metal disk attached to a front end of the fan body, wherein the metal disk comprises an annular disk body in the form of a flat plate, teeth, configured for speed detecting, extending outwards around a circumference of the annular disk body, and a braking surface formed by a front surface of the annular disk body.

In a preferred embodiment of the invention, the teeth of the metal disk comprise a plurality of teeth arranged uniformly along a circumferential direction of the metal disk.

In a preferred embodiment of the invention, the teeth of the metal disk are coplanar with the disk body.

In a preferred embodiment of the invention, the fan body has protrusions which are embedded into notches between the teeth of the metal disk.

In a preferred embodiment of the invention, the notches between the teeth are shaped and sized to mate with the protrusions of the fan body.

In a preferred embodiment of the invention, each tooth of the metal disk has a tip portion which is curved relative to the disk body and embedded into the material of the fan body.

In a preferred embodiment of the invention, the total number of the teeth is 12 or 24. Of course, any suitable number of teeth can be used as desired.

In a further aspect of the invention, a power tool comprising a fan mentioned above is provided.

In a preferred embodiment of the invention, the power tool further comprises a speed detector facing towards the teeth of the metal disk of the fan.

In a preferred embodiment of the invention, the power tool further comprises a braking bolck facing towards a braking surface of the metal disk of the fan.

Brief Description of Drawings

The above and other features and advantages will now be described with reference to embodiments of the invention in conjunction with the drawings, in which:

Figure 1 is an exploded structural view of a fan according to one embodiment of the invention.

Figure 2 is an illustration of a speed detection application of a fan according to the invention.

Figure 3 is an illustration of a mechanical braking application of a fan according to the invention.

Detailed Description of Preferred Embodiments

Some preferred embodiments according to the invention will be described now with reference to the figures.

For clarity and simplicity, like reference numbers in various figures represent the same or similar functional or structural elements.

Hereinafter, a directional term "back" or "backward" refers to a direction from a metal disk towards a rotor of a power tool, and a directional term "front" or "forward" refers to a reverse direction thereof.

With reference to Figure 1 which shows an exploded view of a fan structure according to one embodiment of the invention, a fan as illustrated can be used for a circle raw, an angle grinder, a marble cutter or other power tools.

According to this embodiment, the fan 3 may comprises a metal disk 1 and a fan body 2. The left part of Figure 1 shows the structure of the metal disk 1, the middle part of Figure 1 shows detail structure of the fan body 2, and the right one of Figure 1 shows the fan 3 (with the metal disk 1 mounted on the fan body 2).

The metal disk 1 shown in the left part can be made of a magnetic metal, and it has a high resistance to wear and a high heat conductivity. For example, the metal disk 1 can be formed of a sheet metal.

In Figure 1 , the metal disk 1 is formed into a generally circular shape and has an inner through-hole 11 at its centre through the sheet metal. An outer circumferential surface of the generally circular metal disk 1 is configured for mating with an inner surface of a front-end outer circumferential edge of the fan body 2. An inner surface of the inner through-hole 11 is configured for mating with an outer surface of a hub portion 22 of the fan body 2. According to some embodiments, the metal disk 1 can have other shapes and sizes suitable for mating with the inner surface of the front-end outer circumferential edge of the fan body 2. According to some embodiments, the inner through-hole 11 can have other shapes and sizes suitable for mating with the outer surface of the hub portion 22 of the fan body 2.

For example, in the example illustrated in Figure 1, the metal disk 1 is formed with teeth like projections around its circumference that extend radially outwards. In other words, the metal disk 1 has a plurality of teeth 12 uniformly arranged around its circumference, and indentations or notches 13 formed between neighboring teeth.

In this embodiment, the indentation or notch 13 between each pair of neighboring teeth has a generally arc shape and extends radially inwards from the outer circumferential surface of the metal disk 1. Each tooth 12 is sized to be tapered from the root of the tooth 12 towards the tip of the tooth 12. The notches 13 are shaped and sized to mate with surface projections 24 of the fan body 2. According to some embodiment, the notches 13 can have other shapes and sizes suitable for mating with the surface projections 24 of the fan body 2.

Generally, the total number of the teeth 12 is 12 or 24. In this embodiment, 12 teeth are provided, and alternatively, other number of teeth can be provided for the metal disk 1 as desired.

In the middle part of Figure 1, the fan body 2 according to this embodiment is shown. The fan body 2 can be, for example, a fan body generally used for a circular raw, an angle grinder, a marble cutter or other power tools. For example, the fan body 2 can be made of Nylon (including fibre reinforced Nylon), plastics (including fibre reinforced plastics) or other materials through which magnetic fluxes can pass. The metal disk 1 can be molded as an insert into the fan body 2.

In the illustrated embodiment, the metal disk 1 is secured to the fan body 2 through the engagement of the surface projections 24 of the fan body 2 with the notches 13 of the metal disc 1. However, any other suitable methods can be used for securing the metal disk 1 on the fan body 2, for example, through other form fit structures or using fasteners etc.

For example, in the illustrated embodiment, the metal disk 1 is a generally flat plate, that is, the metal disk 1 has a disk body in the form of the generally flat plate, and the teeth 12 are located in a plane defined by the metal disk 1. However, each tooth 12 can have a tip portion that is curved relative to the flat plate shaped body of the metal disk 1 so as to extend out from the plane defined by the metal disk 1 and be embedded into the material of the fan body 2. In this case, the surface projections 24 can be omitted.

It can be seen from Figure 1 that the fan body 2 has the outer circumferencial edge 21 and the front-end hub portion 22.

The fan body 2 has an end surface 23 with a recess extending into the end surface 23 along an axial direction, and the metal disk 1 is fitted into the recess. As shown in the middle part of Figure 1, the recess has a thickness no less than that of the metal disk 1 so that the metal disk 1 does not extend beyond the fan body 2 when mounted on the fan body 2. The surface projections 24 extend from an inner circumferential surface of the front-end outer circumferencial edge 21 towards the centre of the fan body 2 so as to closely rest against an inner surface of the recess, as shown in Figure 1. The surface projections 24 are shaped and sized to be embedded into the corresponding notches 13 between the teeth of the metal disk 1 , and each surface projection 24 has a thickness less than that of the recess, but greater than that of the metal disk 1, so that the metal disk can function in a better way when mounted on the fan body 2.

Generally, the total number of surface projections 24 is 12 or 24 so as to correspond to the number of coorperating teeth of the metal disk 1. In this embodiment, the number of surface projections 24 and the number of teeth are shown as 12. Additionally and alternatively, other number of surface projections 24 can be used to coorperate with corresponding number of the teeth of the metal disk 1

The front-end hub portion 22 of the fan body 2 has a size and a shape that are suitable for mating with the inner through-hole 11 of the metal disk 1 so as to mate with it when the metal disk 1 is mounted to the fan body 2. A portion of the front-end outer circumferencial edge 21 that extends outwards along the axial direction relative to the recess in the end surface 23 has an inner surface that is sized to mate with the outer circumferential surface of the metal disk 1 so as to mate with the outer circumferential surface of the metal disk 1 when the metal disk 1 is mounted to the fan body 2.

As shown in the right part of Figure 1, the metal disk 1 can be securely fixed on the fan body 2 when mounted to it. The inner surface of the inner through-hole 11 of the metal disk 1 mates with the outer surface of the front-end hub portion 22 of the fan body 2, the outer circumferential surface of the metal disk 1 mates with the inner surface of the portion of the front-end outer circumference 21 of the fan body 2 that extends outwards along the axial direction from the recess in the end surface 23, and the notches 13 on the outer circumferential surface of the metal disk 1 mate with the surface projections 24 in the recess of the fan body 2 at the end surface 23. In this way, the metal disk 1 can be securely fitted onto the fan body 2, that is, onto a rotor 5 of a power tool, through mating the metal disk 1 with the fan body 2. Thus, the metal disk 1 rotates with the fan body 2 and the rotor 5, the metal disk 1 having the same speed of rotation as the fan body 2, and therefore, the rotor 5 can be stopped through stopping the metal disk 1.

In addition, it can be seen from Figure 1 that a majority of a front surface of the metal disk 1 is exposed outside the fan body 2 when the metal disk 1 is mounted on the fan body 2. Thus, a sufficial surface area can be used for coorperating with, for example, a braking disc configured for braking.

In a first application according to the invention, the fan 3 can be used for speed detection of the rotor, as shown in Figure 2. The application of the fan 3 for speed detection according to this embodiment will be explained with reference to Figure 2 now.

With reference to Figure 2, the fan 3 as described above and the rotor 5 are shown. Merely for clarity, a small block in Figure 2 indicates a speed detector, and reference number 6 in Figure 2 is used for identifying the speed detector for speed detecting.

The speed detector 6 can be a conventional speed detector that is used widely in the art. The speed detector 6 is connected to an information display system such as a display or an information processing system such as a computer.

In Figure 2, the fan 3 is shown to be assembled with the rotor 5 in a way of rotating together, and thus the speed of rotation of the fan 3 is equral to that of the rotor 5. The fan 3 has the same speed of rotation as the rotor 5 because the metal disk 1 is securely mated with the fan body 2. In Figure 2, the mounted speed detector 6 is shown adjacent to an outer periphery of the fan 3. The speed of rotation of the metal disk 1 and thus of the rotor 5 can be determined by the speed detector 6 through detecting number of the teeth that pass by the speed detector 6 per unit of time.

The speed detector 6 can feedback information about the speed of rotation of the rotor 5 to any system that communicates with the speed detector 6 after the information is detected by the speed detector 6.

In a further application according to the invention, the fan 3 can also be used for mechanical braking, as shown in Figure 3. The use of the fan 3 for mechanical braking according to this embodiment will be explained with reference to Figure 3

With reference to Figure 3, the fan 3 described above and the rotor 5 are shown. Merely for clarity, reference number 4 in Figure 3 indicates a braking block for mechanical braking.

Similar to that shown in Figure 2, the fan 3 in Figure 3 is shown to be assembled with the rotor 5 in a way of rotating together, and thus the speed of rotation of the fan 3 is equral to that of the rotor 5. A metal disk 1 and therefore the rotor 5 of a power tool can stop rotating due to the fact the metal disk 1 is securely mated with the fan body 2.

When the rotor 5 is to be stopped, the braking block 4 is pushed against the metal disk 1, for example, through a mechanical force or an electromagnetic force or a force in other forms, as shown in Figure 3. The front surface of the metal disk 1 coming into contact with the braking block 4 is considered as a braking surface. The metal disk 1 stops rotating, and therefore the fan 3 and the rotor 5 are stopped. Alternatively, for stopping the rotor 5 more rapidly, a blaking block with larger contacting area, for example, an annular braking block, can be used. Two positions of the braking block are shown in Figure 3, the two positions as shown including, on one hand, a non-braking position in which the braking block 4 is apart from the metal disk, and on the other hand, a braking position in which the braking block 4 is pushed against the metal disk.

To improve the braking effect, a portion of the front surface of the metal disk 1 that is opposite to the braking block 4 can be performed with a surface treatment so as to improve the durability and braking reliability of the metal disk 1.

According to the embodiments of the invention, a metal disk 1 is securely fixed to a fan body 2 through the mating effect of an outer circumferential surface, through the mating effect of notches 13 and through the mating effect of an inner through-hole 11. Due to the fact that the material of the metal disk 1 is a magnetic material and the material forming the fan body 2 is suitable to be penetrated through by magenatic fluxes, the speed of rotation of a rotor 5 can be determined by detecting that of the metal disk 1.

According to the embodiments of the invention, good braking effect can be obtained through securely engagement of a metal disk 1 with a fan body 2, and the rotor 5 can stop rotating accordingly.

According to the invention, a metal disk 1 mounted on a fan body 2 can used for speed detection and mechanical braking at the same time.

A fan according to the invention can be used in any suitable power tool, and all power tools with such a fan are included in the scope of the invention.

Although some special embodiments have been described above, they are presented only by examples, merely for the purpose of illustrating, and are not intended to limit the scope of the invention. Rather, the structure described herein can be embodied in many other forms, and various alternations and changes can be made to the structures and forms described herein without departing from the spirit or scope of the invention.

Claims

1. A fan for a power tool comprising a fan body made of a plastic material and a metal disk attached to a front end of the fan body, wherein the metal disk comprises an annular disk body in the form of a flat plate, teeth, configured for speed detecting, extending outwards around a circumference of the annular disk body, and a braking surface formed by a front surface of the annular disk body.

2. The fan according to claim 1, characterized in that the teeth of the metal disk comprise a plurality of teeth arranged uniformly along a circumferential direction of the metal disk.

3. The fan according to claim 2, characterized in that the teeth of the metal disk are coplanar with the disk body.

4. The fan according to claim 3, characterized in that the fan body has protrusions which are embedded into notches between the teeth of the metal disk.

5. The fan according to claim 4, characterized in that the notches between the teeth are shaped and sized to mate with the protrusions of the fan body.

6. The fan according to claim 2, characterized in that each tooth of the metal disk has a tip portion which is curved relative to the disk body and embedded into the material of the fan body.

7. The fan according to claim 2, characterized in that the total number of the teeth is 12 or 24.

8. A power tool comprising a fan according to any one of claims 1 to 7.

9. The power tool according to claim 8, further comprising a speed detector facing towards the teeth of the metal disk of the fan.

10. The power tool according to claim 9, further comprising a braking block facing towards a braking surface of the metal disk of the fan.