GB2340056A

GB2340056A - Cyclone and filter combination for dust removal

Info

Publication number: GB2340056A
Application number: GB9913207A
Authority: GB
Inventors: Justus Lamprecht; Henning Kasper
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1998-06-18
Filing date: 1999-06-07
Publication date: 2000-02-16
Anticipated expiration: 2019-06-07
Also published as: GB9913207D0; GB2340056B; DE19827173A1; JP2000006054A; CH693501A5

Description

2340056 Extraction device for a hand tool machine

Background art

The invention proceeds from an extraction device for a hand tool machine, in particular for a chipping or drilling hammer, according to the preamble of claim 1.

In a known chipping or drilling hammer havmig an extraction device of said type (DE 40 24 022 AI), the extraction device comprises a suction head, which is arranged concentrically with the chipping or drilling tool 'in the latter's machining range and connected by an external suction line to the separating device. A fan impeller disposed downstream of the separating device generates an air flow which sucks the material (chippings or drillings) removed from the machining point at the tool tip through the suction head and the suction line into the separating device, where dust and removed material are collected 'in a filter bag or folded filter. The filter may be a sintered plastic filter with concertina walls, which is rigid and incompressible, a Teflon-coated paper filter, a paper filter comprising a plurality of layers of paper with nonwoven inserts or a fabric filter manufactured from textiles. The filter is disposed in a cavity, which is provided specifically for said purpose in the housing of tile hand tool machine and is accessible for filter changing purposes via a lid, which may be swung open by means of a hinge. With increasing loading of the filter with dust and removed 25 material, the suction pressure of the fan markedly diminishes so that to guarantee a satisfactory extraction of dust and removed material, the filter has to be changed frequently and, moreover, before it has reached its maximum filling capacity.

2 Advantages of the invention The extraction device according to the 'invention having the features of claim 1 has the advantage that, by virtue of the preliminary separating chamber, the filter is s loaded less and hence has a much longer life and so the filter changing cycle is substantially prolonged. By virtue of the cyclonic separationmi the preliminary chamber, the removed material is collected in the collecting container and only the fine dust passes into the filter. The suction pressure of the fan consequently remains unaffected at its maximum level, and indeed does so until the capacity of the collecting contamier is exhausted. It is only then that removed material also passes into the filter and the loading of the latter markedly increases, resulting in a drop in the suction power. Because of the considerably reduced loading of the filter the filter may, despite a longer life, be made smaller.

is Advantageous developments and improvements of the extraction device indicated in claim I are possible by virtue of the measures outlm'edm' the further claims.

According to an advantageous embodiment of the mivention, all wall surfaces of the preliminary chamber and of the immersion pipe are smooth and all edges of preliminary chamber and u'runersion pipe at which a higher flow rate arises are rounded. As a result, the maximum suction power of the extraction fan may be fully utilized to transport dust and removed material into the collecting container and said dust and removed material are prevented from settling at undesirable points of the suction path.

2S According to a prefer-red embodiment of the invention, the funnel-shaped immersion pipe projects axially into the preliminary chamber from the end remote from the open end of the preliminary chamber, and the mouth of the air inlet connection piece in the prelimi,nary chamber lies inside the immersion region of the immersion pipe, preferably adjacent to the funnel base. The preliminary chamber is disposed centrally inside the collecting container in such a way that its open end lies with clearance 'in front of the container base, and the collecting container has a rectangular cross section, the smaller side of which is slightly greater than the outside diameter of the enclosed preliminary chamber. Said constructional design of the collecting container leads to the formation, on either side of the preliminary chamber, of two secondary chambers which on the one hand increase the capacity of the collecting container given a compact design of the separating device and on the other hand guarantee that, during vertical drilling or chipping in an upward or downward direction, there is no settling of dust and removed material in the preliminary chamber so that preliminary separation through the cyclone effect remains available.

Drawmgs There follows a detailed description of an embodiment of the invention which is illustrated 'in the drawings. The drawings show:

Fig. I a longitudinal section of an extraction device for a chipping or 'drilling hammer, Fig. 2 a section along the line U-11 in Fig. 1, Fig. 3 in a cutout manner a chipping harnmer in normal position during chipping of a vertical wall.

Description of the embodiment

4 The extraction device illustrated in Fig. I in conjunction with Fig. 3 for a chipping hammer serving as an embodiment of a hand tool machine for effecting cutting, drilling, grinding, sawmig, chipping or combined drilling and chippig of a workpiece comprises a suction head I I (Fig. 3) arranged concentrically with the chipping tool 10 in the latter's machining range, a separating device 12 (Fig. 1) as well as an extraction fan 13. The suction head 11 is connected by a suction line 14 to the separating device 12, and the extraction fan 13 is disposed in air flow direction downstream of the separating device 12. The extraction fan 13 comprises a blower- or fan impeller 15, which is designed as a radial fan with axial air intake and radial air discharge and is driven via a bevel gearing by the electric drive motor for the chipping tool 10 of the chipping hammer.

The separating device 12 comprises a cylindrical preliminary chamber 16 which, for generating a cyclone effect comprises a tangential inlet connection piece 17 is connected to the suction line 14 and a coaxial, central, funnel-shaped immersion pipe 18, the clear cross section of which viewed 'in air flow direction progressively increases, a filter 19 which is disposed in air flow direction downstream of the preliminary chamber 16 and may be, for example, a folded paper filter, as well as a collecting container 20 which is connected to the open end 161 of the preliminary chamber 16 remote from the immersion pipe 18. All wall surfaces of the preliminary chamber 16 and of the immersion pipe 18 are smooth and all edges of preliminary chamber 16 and immersion pipe 18 at which a high flow rate arises are rounded.

The preliminary chamber 16 with fannel-shaped immersion pipe 18 is integrated in the collecting container 20 and integrally formed therewith, the immersion pipe 18 being uirnmersed axially into the preliminary chamber 16 from the end remote from the open end 161 of the preliminary chamber 16 and the mouth 171 of the air inlet connection piece 17 in the preliminary chamber 16 lying inside the immersion region of the immersion pipe 18, and indeed adjacent to the fimel base. The preliminary chamber 16 is in said case disposed centrally 'inside the collecting contamier 20 in such a way that its open end 161 lies with clearance in front of the container base 20 1. The container base 201 is pivotally supported on the collecting container 20 and-latched by means of a latching device 21 on the collecting container 20. As Fig. 2 reveals, the collecting container 20 has a rectangular cross section, its smaller side being slightly greater than the outside diameter of the preliminary chamber 16 enclosed by the collecting container 20 so that there is formed, on either side of the preliminary chamber 16, a secondary chamber 22 for the precipitation of removed material.

Adjacent to the wall 202 of the collecting container 20, which wall has the outlet opening 181 of the immersion pipe 18 and extends parallel to the container base 201, a filter chamber 25 for receiving the filter 19 is formed, which is open at the opposite side and closable by means of a lid 23. The lid 23 is fastened to the collecting container 20 so as to be capable of swivelling about the swivellmig axis 24 and in its closed position, "in which it covers the secondary chamber 22 with the intercalation of a ring seal 30, is latchable on the collecting contamier 20 in a manner not shown in detail here. Centrally in the lid 23 the fan impeller 15 is rotatably supported and an expansion spiral 29 formed, which is used to convert the velocity energy generated by the fan impeller 15 into compression energy.

In Fig. 1, the separating device 12 with preliminary chamber 16, collecting container 20 and filter chamber 25 is shown in longitudinal section in the normal operating position of the chipping hammer as revealed in Fig. 3. In said normal operating position of the chipping hammer, a hole 26, for example, is knocked into a vertical concrete wall 27 and the dust and chippings 28 arising are extracted by 6 means of the extraction device from the working range of the chipping tool 10.

During harnmening or chipping the fan impeller 15 generates an air flow, which sucks dust and chippings 28 at high speed through the suction head 11 and the suction line 14 connected to the air inlet connection piece 17 into the separating S device 12, where dust and chippings 28 are collected and removed from the air flow. By virtue of the cyclone effect generated in the prelIMM' ary chamber 16, the heavier chippmigs 28 strike against the cylindrical inner wall of the preliminary chamber 16 and drop into the secondary chambers 22, which increasingly fill with chippings 28, as is shown in Fig. 1. The much lighter dust passes with the air flow into the central immersion pipe 18 and through the latter's outlet opening 181 into the filter 19. The dust is retained in the filter 19, while the suction air passes through the filter 19 and, having been relieved of pressure by means of the expansion spiral 29, exits through openings 'in the lid 23 which are not shown here. Once the secondary chambers 22 are extensively full of chippigs 28, the effect of the cycloruic separation of the chippings 28 diminishes and increasingly more chippings; 28 pass through the ninmersion pipe 18 into the filter 19. Once the latter is fully loaded, which is apparent from the markedly reduced suction power of the extraction fan 13, the filter 19 has to be changed and the chippings 28 removed from the secondary chambers 22. To do so, the container base 201 has to be swung open and the lid 23 has to be swivelled upwards to change the filter.

During vertical chipping of a floor or ceiling, the collecting container 20 permanently integrated in the housing of the chipping hammer occupies a position rotated through 90' in an anti-clockwise or clockwise direction. In said position 2S also, the preliminary separation of chippigs 28 through the cyclone effect of the preliminary chamber 16 remains capable of functioning because the chippIngs 28 settle in each case in the lower-lying secondary chamber 22 and a performanceimpairing loading of the preliminary chamber 16 is avoided.

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Claims

1. Extraction device for a hand tool machine, in particular for a chippmig or drilling hammer, having an extraction fan (13) -and having, downstream thereof, a separating device (12) for dust and removed material (28), in particular chippings or drillings, which comprises a filter (19), characterized in that disposed upstream of the filter (19) is a cylindrical preliminary chamber (16) which, for generating a cyclone effect, comprises a tangential air inlet connection piece (17) and a coaxial, central funnel-shaped immersion pipe (18), and that the preliminary chamber (16) is open at its end remote from the immersion pipe (18) and is connected to a collecting container (20).

2. Device according to claim 1, characterized in that the clear cross section of the immersion pipe (18) progressively increases 'in air flow direction.

3. Device according to claim I or 2, characterized in that all wall surfaces of the preliminary chamber (16) and of the immersion pipe (18) are smooth and all edges of preliminary chamber (16) and immersion pipe (18) at which a high flow rate arises are rounded.

4. Device according to one of claims I - 3, characterized 'in that the immersion pipe (18) is immersed axially into the preliminary chamber (16) from the end remote from the open end ( 16 1) of the preliminary chamber (16) and that the mouth (171) of the air inlet connection piece (17) in the preliminary chamber (16) lies inside the 8 immersion region of the U'rimersion pipe (18), preferably adjacent to the funnel base of the latter.

5. Device according to one of claims 1 - 4, characterized 'in that the preliminary chamber (16) is disposed centrally inside the collecting container (20) in, such a way that its open end (161) lies with clearance 'in front of the container base (201).

6. Device according to claim 5, characterized in that the collecting container (20) has a rectangular cross section, the smaller side of which is slightly greater than the outside diameter of the enclosed preliminary chamber (16).

7. Device according to claim 5 or 6, characterized in that collecting is container (20) and preliminary chamber (16) are formed integrally, preferably from plastic materi al.

8. Device according to claim 7, characterized in that adjacent to the wall (202) of the collecting container (20), which wall has the outlet opening (181) of the immersion pipe (18), a filter chamber (25) for receiving the filter (19) is formed, which is open at the opposite side and closable by means of a lid (23).

9. Device according to claim 8, characterized Mi that a fan impeller 2S (15) of the extraction fan (13) with axial air intake and radial air discharge is rotatably supported 'in the lid (23).

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10. Device according to claim 9, characterized in that the fan impeller (15) is disposed in an expansion spiral (29).

11. Device according to one of claims 8 - 10, characterized 'in that a ring seal (30) is inserted between filter chamber (25) and lid (23).

12. Device according to one of claims I - 11, characterized 'in that the collecting container (20) is integrated in the machine housing, preferably being formed integrally with the latter.

13. An extraction device for a hand tool machine substantially as herein described with reference to the accompanying drawings.