WO2007093123A1

WO2007093123A1 - Cyclone for cleaning dust polluted air coming from a power tool

Info

Publication number: WO2007093123A1
Application number: PCT/CN2007/000519
Authority: WO
Inventors: Gianni Borinato
Original assignee: Positec Power Tools (Suzhou) Co., Ltd.
Priority date: 2006-02-16
Filing date: 2007-02-14
Publication date: 2007-08-23
Also published as: CN101020164B; CN101020164A

Abstract

The cyclone (4) is determined for collecting dust laden air (a) from a power tool, such as from a saw or a belt sander. It comprises a cylindrical body (6) and a conical body (8) which have a main axis (16) that is oriented substantially horizontally during operation. It comprises also a dust outlet (18; 30, 32, 34) which has an effective outlet area being larger than the circular outlet area which is conventionally provided at the outer end of the conical body (8). The enlarged dust outlet may take the form of dust exit holes (22) in the wall of the conical body (8), or it may take the form of an inclined outlet area.

Description

Cyclone for Cleaning Dust Polluted Air Coming from a Power Tool

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a novel and improved cyclone for collecting dust laden air from a power tool, such as from a saw or from a belt sander, which cyclone comprises a conical body having a main axis and an end section, and which has a dust outlet for releasing dust separated from said dust laden air during operation.

The invention also relates to a dust separator including such cyclone.

2. Description of the Prior Art

Cyclones are widely used in the prior art in order to separate dust and debris from air collected from a tool or home appliance such as a vacuum cleaner. Generally the longitudinal axis of such tool or home appliance is oriented vertically during operation. Thereby, the dust can easily fall down by itself under the force of gravity into a collecting chamber, from which it can be removed from time to time.

It has been found, however, that there may be applications of at least one cyclone in connection with a power tool for the purpose of separating the dust from air and for collecting the dust, in which applications it would be desirable to arrange the cyclone or cyclones in a horizontal position, i.e. in which the longitudinal axis of each cyclone is oriented essentially horizontally during normal operation. This may be due, for instance, to space restrictions, such as requirements with regard to the hight of the entire dust separator including the power tool.

It has also been found by experiments that a conventional cyclone may not work efficiently under such circumstances, since the cyclone may be blocked, stuffed or clogged by dust and other debris after a certain time of operation. Thereby, the dust

i separator may become completely inoperative so that it has to be cleaned in a time- consuming way.

SUMMARY OF THE INVENTION

1. Objects

An object of this invention is to provide a cyclone for use in connection with a dust developing tool, which cyclone shall have a reduced clogging probability when working in a basically horizontal orientation.

Another object of the invention is to provide such cyclone which can easily be produced.

It is still another object of this invention to provide such cyclone for installation in a housing which can easily be attached to a dust developing power tool.

2. Summary

According to a primary solution, the present invention is based on the recognition that a reduced clogging probability can be achieved by enlarging the effective dust outlet area, as compared to the prior art.

Thus, according to this invention the cyclone is characterized in that

- its main axis is oriented substantially horizontally during operation, and

- its dust outlet has an effective outlet area which is larger than a circular outlet area which is conventionally provided at the outer end of its conical body.

According to a first set of embodiments, the cyclone is provided with an outlet, preferably with an outlet having a circular outlet area, at the end of said outlet section of said conical body, and at least one exit hole in the wall of said conical body.

It is preferable to provide at least two exit holes in said wall in a row and in a plane which is perpendicular to said main axis. In such designs, the dust can easily fall down from the exit holes by gravity.

According to a second set of embodiments, the cyclone is characterized in that

said dust outlet comprises an outlet area which is inclined by an angle (alpha) which is at least 10° with respect to a plane that intersects said main axis perpendicularly.

In a preferred embodiment, which can easily be produced, the end portion of said hollow conical body is obliquely cut off to form said dust outlet for emitting dust.

In order to concentrate the dust falling down under the effect of gravity in a heap of limited size, it may be favorable to use a hollow extension piece which is connected to said conical body, said extension piece having an output facing ground during operation.

The dust separator according to the invention includes any of such cyclones.

The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings.

According to a secondary solution, the present invention is based on the recognition that the drop-down of dust can be improved by other means.

Thus, according' to this invention the cyclone is characterized in that

- the beginning section of said conical body is oriented substantially horizontally during operation , and

-in that said end section of said conical body is bent in such a way that said dust outlet faces ground.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, preferred embodiments of the present invention are illustrated. Fig. 1 is a cross-sectional side-view of a dust separator incorporating a cyclone for application to a power tool,

Fig. 2 is a cross-sectional side-view of a cyclone showing three possibilities, symbolized by cut-lines I, Il and III, to generate an enlarged dust outlet area at the end section of the conical body,

Fig. 3 is a perspective side-view of a cyclone being provided with a cut line-Ill,

Fig. 4 is a perspective side-view as shown in Fig. 3, wherein the conical body is provided with a first extension piece,

Fig. 5 is a perspective side-view as shown in Fig. 3, wherein the conical body is provided with a second extension piece,

Fig. 6 is a cross-sectional side-view of another embodiment having an inclined conical body, and

Fig. 7 is a cross-sectional side view of a conical body having a bent end section.

DETAILED DESCRIPTION OF THE DRAWINGS

In Fig. 1 the principle of a dust separator or filter unit 2 incorporating the present invention is illustrated. The unit 2 is associated with a tool (not shown) which develops a lot of dust d in the air attracted from the environment during operation. The unit 2 is attached to the tool by an attachment device not shown, such as a screwing or a clamping device. It must be stressed that the filter unit 2 can be used in connection with all kinds of power tools, such as sanders and saws which emit air a polluted with dust d from a working piece.

The dust d has to be removed from the air a before the air a can be released as clean air a^' to the surroundings. For this purpose the dust filter unit 2 contains a cyclone 4 which comprises a cylindrical body 6, a conical body 8 attached thereto, a peripheral entrance tube 10 having an entrance 11 for air a and dust d derived from the tool, an air exit tube 12 having an exit 13, and a closed housing 14 which houses the elements 4 to 12. A door for removing dust d from the housing 14 is not specifically shown. The entrance of the cylindrical air exit tube 12 lies inside the cylindrical body 6, whereas the exit 13 lies outside. The central or main axis of the bodies 6, 8 and the air exit tube 12 is denoted as 16. The housing 14 may have a conical or rectangular shape. It will be realized that the cyclone 4 is arranged in an approximately horizontal position during operation. This horizontal arrangement is parallel due to various reasons, such as to space restrictions or convenience in handling in association with the power tool.

As in the conventional design of a cyclone 4, there is provided a conventional mouth or outlet 18 having a ring-shaped output surface or circumference at the outer end of the conical body 8. According to the invention, this mouth 18 determines only a portion of the entire effective outlet area for dust d of the cyclone 4.

The operation of the cyclone 4 is such that the dust d laden air a enters the cyclone 4 via the entrance tube 10. Within the cyclone 4 it is separated into clean air a^' released from the exit 13 and dust d released partially from mouth 18 and accumulated at the bottom of the housing 14 is a heap 20.

It must be emphasized that a plurality of support mouths or exit holes 22 (only two of them are shown) are provided in the wall of the conical body 8. They are also determined for emitting dust d to the pile 20. Here they are provided in a row on the lower side of the wall and in a plane which is perpendicular to the main axis 16. They may be located close to the end of the conical body 8, i.e. close to the conventional end mouth 18. They may take the form of circular holes. These additional mouths or exit holes 22 constitute another portion of the entire effective outlet area of the cyclone 4. Thus, they enlarge the entire outlet area, thereby improving and accelerating the release of dust d from the cyclone 4 and thereby preventing clogging.

It will be appreciated that the conventional exit 18 may be avoided and that such outlet holes 22 may be sufficient for releasing enough dust d from the cyclone 4, provided that their combined outlet area is larger than that of the otherwise applied additional outlet area of the outlet 18. The effective area in this case is constituted by the outlet areas of the outlet holes 22 only.

According to Fig. 2 a cyclone 4 of conventional design comprises a cylindrical body 6 and a conical body 8 which have a main axis 16 which is oriented horizontally during operation. At the outer end of the end section of the conical body 8, the conventional dust outlet 18 having a circular dust outlet area is shown.

In order to increase the effective outlet area, three possibilities characterized by straight cut-lines I, II, III (symbolizing corresponding planes) at the end section are illustrated. All three cut-lines I, II, III are thought to cut off an end portion of the conical body 8. Each of them generates an outlet area which is inclined by an angle alpha with respect to a plane 24 that intersects the main axis 16 perpendicularly. This angel alpha should be at least 10°. Thus, three dust outlets 30, 32, 34 of different size and/or shape are formed.

The dust outlet 30 is a comparatively large outlet having an oval shape. The dust outlet 32 is a smaller outlet having also an oval shape. And the dust outlet 34 is an outlet having partially a semi-oval shape, as is illustrated in Figs. 3 - 5. The inclined outlet area of each the outlets 30, 32, 34 faces towards ground during operation. In all three cases the cut-away portion, i.e. the recess, increases the possibility and speed for the dust d to drop downwards and to accumulate in the heap 20. Thus, the possibility of clogging is considerably reduced.

In order that the user may be able to check easily the situation in the conical body 8, this body 8 and the housing 14 may be made of a light-transparent plastic material.

In Fig. 3, the embodiment in accordance with cut-line III of Fig. 2 is illustrated in a perspective view. As can be seen, in this embodiment the effective dust exit surface is enlarged by cutting off a lower portion of the wall of the outer end of the conical body 8. Thus, the dust outlet 34 contains a recess 36 having a rim which is partially ellipsoidal. The major portion of the separated dust d can escape via this recess 36 under the force of gravity when the cyclone 4 is in a horizontal position. Fig. 4 is basically the embodiment shown already in Fig. 3. Yet, in this embodiment a hollow extension piece 38 is connected to the rim of the recess 36 of the dust outlet 34. The extension piece 38 has a dust output 40 which directly faces ground during operation. The side walls of the extension piece 38 meet each other in an ellipsoidal rim which forms the dust output 40.

In contrast to Fig. 4, the connecting piece 38 of Fig. 5 has non-joining side-walls such that the dust output 40 is semi-elliptical.

The pieces 6, 8 and 38 may consist of a plastic material so that they can be molded together. A plastic material of light weight should be chosen.

It has been observed that during work on specific materials electrostatic problems may arise. The result is a growing layer of such material on the entire inner surface of the cyclone. Such problems may even arise when dust of specific kinds of wood shall be filtered out of the polluted air. In order to alleviate this problem, it has been found that a spray which contains an electrically conductive material should be sprayed onto the entire inner surface of the cyclone 4 to form a layer 42. Such layer 42 is partially illustrated in Fig. 1 on the bodies 6 and 8.

According to Fig. 6 , which is similar to Fig. 2, the main axis 16 of the conical body 8 is bent downward by a small angle β. The inclined dust outlet is denoted as 44. Thus, the angle β characterizes the inclination of the main axis 16 with regard to the horizontal plane 46.

In Fig. 7, the conical body 8 is shown to comprise a beginning section 48 and an end section 50. While the beginning section 48 is oriented horizontally during operation, the end section 50 is bent downward. Thus, the dust outlet 52 faces ground. It may be basically parallel to the horizontal plane 46, and it may have an oval output area, as illustrated in Fig. 7.

Claims

Patent Claims

1. A cyclone (4) for collecting dust laden air (a) from a power tool, such as from a saw or from a belt sander, comprising a conical body (8) having a main axis (16) and an end section, and having a dust outlet for releasing dust (d) separated from said dust laden air (a) during operation, characterized

- in that said main axis (16) is oriented substantially horizontally during operation, and

- in that said dust outlet (18; 30, 32, 34, 44) has an effective outlet area which is larger than a circular outlet area which is conventionally provided at the outer end of said conical body (8).

2. The cyclone (4) according to claim 1, wherein there is provided an outlet (18), preferably an outlet (18) having a circular outlet area, at the end of said outlet section of said conical body (8), and wherein the wall of said conical body (8) has at least one exit hole (22).

3. The cyclone (4) according to claim 2, wherein at least two exit holes (22) are provided in said wall in a row and in a plane which is perpendicular to said main axis (16).

4. The cyclone (4) according to one of the preceding claims, characterized

in that said dust outlet (30, 32, 34, 44) comprises an outlet area which is inclined by an angle (alpha) which is at least 10° with respect to a plane (24) that intersects said main axis (16) perpendicularly.

5. The cyclone (4) according to one of the claims 1 to 4, wherein the end portion of

said hollow conical body (8) is cut off to form said dust outlet (30, 32, 34, 44) for

emitting dust (d).

6. The cyclone (4) according to claim 5, wherein said outlet area of said outlet (34, 44) comprises a partially circular area.

7. The cyclone (4) according to claim 5, wherein said outlet area of said outlet (30,

32, 44) is an oval area.

8. The cyclone (4) according to one of the preceding claims, wherein said conical

body (8) is of a light transparent plastic material.

9. The cyclone (4) according to one of the preceding claims, wherein a hollow

extension piece (38) is connected to said conical body (8), said extension piece

(38) having an output (40) facing ground during operation.

10. The cyclone (4) according to one of the preceding claims, wherein said conical

body (8) is connected to a cylindrical body (6) having an entrance tube (10) for

dust laden air and an air exit tube (12).

11. The cyclone (4) according to one of the preceding claims, wherein said cyclone is

contained in a housing (14).

12. The cyclone (4) according to claim 10 and 11, wherein said cylindrical body (6) is

supported in said housing (14) by said entrance tube (10) and/or said air exit tube

(12).

13. The cyclone (4) according to one of the preceding claims, wherein a layer (42) of

an electrically conductive material is provided on at least the inner surface of said

conical body (8).

14. The cyclone (4) according to claim 13, wherein said layer (42) is produced by

spraying.

15. The cyclone (4) according to any of the preceding claims, wherein said main axis (16) deviates by a predetermined angle (beta) from a horizontal plane (46).

6. A cyclone (4) for collecting dust laden air (a) from a power tool, such as from a saw or from a belt sander, comprising a conical body (8) having a main axis (16) and an end section, and having a dust outlet for releasing dust (d) separated from said dust, laden air (a) during operation, characterized

- in that the beginning section (48) of said conical body (8) is oriented substantially horizontally during operation , and

- in that said end section (50) of said conical body (8) is bent in such a way that said dust outlet (52) faces ground.