GB2393143A

GB2393143A - Hand held machine tool with detachable dust box

Info

Publication number: GB2393143A
Application number: GB0321994A
Authority: GB
Inventors: Steffen Wuensch
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2002-09-23
Filing date: 2003-09-19
Publication date: 2004-03-24
Anticipated expiration: 2023-09-19
Also published as: FR2844737B1; DE10244085A1; FR2844737A1; GB0321994D0; GB2393143B

Abstract

A hand-held machine tool 10 having a housing 12 and a blowing-out feed-pipe 28 to which a dust box 30 can be detachably fastened with the aid of its connecting feed-pipe 34. The dust box 30 can be equipped in a replaceable manner with a tube-like, in particular rotationally symmetrical filter, in particular a folded filter, and has an outer contour which is adapted thereto. Both the outer annular wall 32, and also the inner annular wall 38 of the dust box 30 have air holes 39 (in one embodiment) and also carry a folded filter 44 which is configured in a tube-like manner. The waste air passes through clearances 41 in the end wall (Fig 4, 40) into the annular dust chamber 33.

Description

GB 2393143 A continuation (56) cont Accession No.97-531295/49 WO

2002/007932 A1 & See esp figs 1,5 & WPI Abstract Accession No.02155145/20 DE 29508874 U & See esp figs & WPI Abstract Accession No.96444187/45 DE 019800045 A1 & See esp fig & WPI Abstract Accession No.98468519/41 (58) Field of Search:

UK CL (Edition V) B3D DEV DHD, B5L LDE, F4X XA2BX XA2E 1 NT CL7 B23D 45/00 47/00, B23Q 11/00, B24B 55/00,

B25F 5/00, B27G 3/00

Other: Online:EPODOC,WPl,PAJ

2393 1 43

Hand-held machine tool with dust extraction 5 The invention starts out from a hand-held machine tool of the type in claim 1.

From WO 00/73016, a hand-held machine tool is known which has a dust box that carries, in an air-permeable, 10 replaceable lid, a folded filter which effectively retains dust, particularly fine dust, and contributes considerably to improving working hygiene and safety. This box-shaped dust box is relatively expensive to manufacture. In addition, there are limits to its filtering and dust 15 extracting capacity.

Compared to the above, the hand-held machine tool with dust extraction according to the invention, which has the features in claim 1, has the advantage that a still lighter 20 and more inherently stable dust box has been provided which possesses a size of filtering surface, an airpermeability and a filtering capacity that have not hitherto been achieved. In addition, the appertaining filter in the form of a cylindrical filter tube can be cost-effectively 25 manufactured, emptied in a convenient and environmentally friendly manner, and easily replaced.

Through the fact that the dust box is configured as a truncated cone or a cylinder, its rear covering surface 30 being constituted by a removable lid, it can be manufactured in a simple manner, is simple to open and can be easily and securely closed, and as a result is convenient to handle.

35 Through the fact that the dust box has a central dust-

collecting compartment and the lid closes off the latter in

an airtight manner, the outer annular wall or cylindrical casing of the dust box may serve as an air-permeable surface and be equipped with a cylindrical or conical filter tube or filter cartridge in a closely adjoining 5 manner.

The filtering capacity of the dust box is improved through the fact that the dust box has a central dust-collecting compartment and the lid has one or more air outlet 10 apertures and carries a dust filter on the inside.

Through the fact that the dust box has an eccentric dust-

collecting compartment with an outer and an inner annular wall, and the lid has an, in particular, central air outlet 15 aperture, the air holes can be placed on the inner annular wall of the annular compartment instead of the outer annular wall, so that said outer annular wall has higher inherent stiffness.

20 Through the fact that both the outer and the inner annular walls of the dust box that form the eccentric dust-

collecting compartment have air holes and are each surrounded by a tubelike folded filter in a leak-proof manner, the filtering capacity, which is already high per 25 se, of a dust box having only a single perforated annular wall is almost doubled.

The dust box can be coupled to the hand-held machine tool in a convenient manner through the fact that it is 30 configured as a stepped cylinder, whose region having the smaller cylinder diameter constitutes the inlet feed-pipe for dust which is being extracted.

Through the fact that there is disposed centrally in the 35 radially inner annular wall, a flow cone whose point is directed towards the air flowing in and directs the latter

radially outwards, particularly into the annular compartment, the flow losses in the interior of the dust box in the course of dust extraction are slight.

5 A particularly large filtering surface can be brought about in a simple manner through the fact that the filter consists of folded-filter paper which is wound in a tube-

like manner.

10 A particularly effective filter is provided through the fact that the filter consists of two concentric folded-

filter tubes, between which an annular compartment, through which dustcontaining waste air can flow, is formed and which are secured in position in relation to one another 15 with the aid of a stiffening plastic corset.

The dust content of the filtered air is minimised through the fact that the flow of waste air is directed, without the possibility of leaking, through the filter which is 20 sealed off, in particular, in relation to the lid and the inflow region.

Because of the plastic corset, the filter is so robust that the dust can be knocked out of it in a convenient manner 25 without any risk of damage.

The invention is explained in greater detail below with the aid of appertaining drawings, in which: 30 Figure 1 shows a partial longitudinal section through the hand-held machine tool with dust box according to the invention; figure 2 shows a longitudinal section through the dust box in the form of a detail; 35 figure 3 shows the cross-section of the dust box in the centre;

figure 4 shows the cross-section of the dust box in the inflow region; figure 5 shows a further exemplified embodiment of the dust box with an outflow region which is disposed in a radially 5 outer manner) figure 6 shows another form of embodiment of the dust box with outflow regions that are disposed in both a radially inner and also a radially outer manner; figure 7 shows a side view of the dust box illustrated in 10 figures 5 and 6i figure 8 shows a cross-section of the dust box illustrated in figure 6; figure 9 shows a longitudinal section through another form of embodiment of a dust box; and 15 figure 10 shows a cross- section of the dust box illustrated in figure 9.

Figure 1 shows the side view of a hand-held machine tool 10 which is configured as an orbital grinder and has a housing 20 12 which has a handle 14 with a switch button 16. A grinding plate 18 with extraction holes 24 and a grinding disc 20 fastened to it is rotatably mounted at the bottom of the housing 12 so as to be capable of being driven about an axis 22 for chip-removing purposes. A flow of air to be 25 extracted, to which no further designation has been given, follows the direction of the flow-indicating arrow 26 and transports the chips and grinding dust that occur away from the working surface through the interior of the housing 12.

At the rear end, the housing 12 has a tube-like blowing 30 out feed-pipe 28, on which a cylindrical dust box 30 is seated with the aid of its connecting feed-pipe 34 so as to be capable of being latched-on or otherwise locked in a captive manner.

35 The hand-held machine tool 10 carries an electrical connecting lead 17 at the rear end of the handle 14, and a

fan wheel, to which no further designation has been given, in the interior of the housing 12. When the hand-held machine tool is in operation, said fan wheel generates a negative pressure under the grinding plate 18 or grinding 5 disc 20. As a result, grinding dust is sucked, when the hand-held machine tool 10 is in operation, through the transition apertures 24 in the grinding plate 18 and blown through the blowing-out feed-pipe 28 and into the dust box 30 via the connecting feed- pipe 34.

Figure 2 shows the stepped cylindrical dust box 30 in the form of a detail. Said dust box has an outer annular wall 32 determining the outer contour and is closed in an airtight manner - apart from the blowing-in or sucking-in 15 aperture 31 of the connecting feed-pipe 34 and the cylindrical, tube-like inner annular wall 38 of said dust box. Said inner annular wall 38 carries a number of regularly distributed, round, air through-holes 39 and, on its radially outer side, a tube-like, accordionpleating 20 like folded filter 44 made of special paper. The folded filter 44 faces towards the inner annular wall 38 with its outer side, and towards the interior of the annular dust chamber 33 with its inner side.

25 At its free front end, the dust box 30 carries a lid 42 and, at the opposite end, merges with its outer end wall 29, in a manner which is arched radially inwards, into a smaller cylinder which constitutes the connecting feed-pipe 34 for coupling to the hand-held machine tool 10, or to the 30 blowing-out feed-pipe 28, and which carries the blowing-in aperture 31.

With its outer rim 48, the annular lid 42 engages round the tube-like outer annular wall 32 of the dust box 30 in an 35 airtight manner and is fixedly held thereon, particularly surprisingly, in a captive manner. With an inner rim 46,

the lid 42 grips onto the tube-like inner annular wall 38 in a detachable and airtight manner, the central aperture 43 in the annular lid 42 serving for the egress of the waste air which has been freed from dust and which has 5 previously passed through the filter 44 and the air holes 39. It is also possible, for example, for the extraction feed-pipe of a vacuum cleaner hose to be slipped into the central aperture 43, and for the extraction of dust to thus be augmented in a simple manner.

In the interior of the dust box 30 or of the inner annular wall 38, at the front, there is disposed, in a sealed-off manner and so as to merge with its outer contour into a front inner end wall 40 of the dust box 30, a central, 15 truncated-cone-shaped air-directing body 36 which directs the dust-containing waste air coming from the blowing-out feed-pipe 28 radially outwards into the annular compartment 33 between the outer and inner annular walls 32, 38 with a minimal loss of flow. For that purpose, the waste air 20 passes through clearances 41 in the inner end wall 40, which is perforated many times or is net-like, of the dust box 30 and into the annular compartment 33, passes at that point through a folded filter 44 supported in a leakproof manner on the inner annular wall 32, and leaves the dust 25 box 30 axially towards the rear and towards the outside through the air holes 39 in the inner annular wall 32 via the tube-like inner compartment of the inner annular wall 38. For the purpose of spacing-apart and stabilising the annular walls 32, 38, the latter are connected to one 30 another radially via an inner end wall 47 which is perforated many times and through which, after removal of the lid 42, it is possible to empty the accumulated dust which had collected, with the waste air, upstream of the filter 44.

Figure 3 shows a cross-section through the dust box 30

illustrated in figure 2, cut approximately in the centre of the longitudinal extent in accordance with the section-

indicating arrows B-B. As a result, it is possible to make out particularly clearly the concentric disposition of the 5 outer and inner annular walls 32, 38, of the air holes 39 and of the inner annular wall 38, and the disposition of the folded filter 44 in the annular compartment 33 between the outer and inner annular walls 32, 38. The folded filter 44 is folded in the form of a meander and engages, 10 with its regions that are located radially on the inside, round the outer surface of the inner annular wall 38 in a sealing manner. As a result, the dust-containing air is forced to pass through the folded filter 44 before it leaves the dust box 30 towards the outside through the air 15 holes 39.

Figure 4 shows a cross-section through the dust box 30 corresponding to the sectional arrows A-A illustrated in figure 2, upstream of the inner end wall 40. It is thereby 20 possible to make out the spoke-like structure of said inner end wall 40 through which the waste air is able to flow into the interior of the annular compartment 33. Also provided therein is a cut-away plan view of the air-

directing body 36 which directs the waste air flowing in at 25 the front radially outwards into the interior of the annular space 33 in a manner favourable to flow.

Figure 5 shows a longitudinal section through another dust box 300 which is basically constructed in the same way as 30 that illustrated in figure 2, but in which the air holes 390 are disposed not on the inner annular wall 380, but on the outer annular wall 320. The latter is sealed off on the inside in a laminar manner with the aid of a folded filter 440, so that dust-containing air is cleaned after 35 passing through. After passing through the connecting feed-pipe 340, the dust-containing air impinges upon the

air-directing body 360 and is directed by the latter radially outwards into the annular space 330 in a manner favourable to flow. There, it flows radially outwards through the air holes 390 and is able to leave the dust box 5 300 in a cleaned condition.

At its rear end, the dust box 300 is closed in an airtight manner on its end face with the aid of a lid 420. On the opposite side - that is to say at the front end - the 10 annular compartment 330 is bounded by an inner end wall 400 which fixes the inner annular wall 380 radially in relation to the outer annular wall 320 and which is air-permeable and admits the dust-containing waste air into the annular compartment 330.

With the aid of its central aperture 430, the lid 420 centres the inner annular wall 380 in relation to the outer annular wall 320.

20 Figure 6 shows another exemplified embodiment of a dust box 3000, which differs from that illustrated in figure 5 only through the fact that the inner annular wall 3800, in addition to the outer annular wall 3200, is provided, like the latter, with air holes 3900. The rest of the 25 construction is identical to that illustrated in figure 5, so that separate reference will not be made again to said construction, nor to the corresponding reference numerals which differ only through an additional "0".

30 Figure 7 shows a side view of the dust box 300 illustrated in figure 5, in which it is possible to make out particularly clearly the distribution of the round air holes 390 over the outer annular wall 320 particularly clearly, which air holes may naturally also be disposed in 35 a different form and distribution, for example, as a pattern of slots.

Figure 8 shows a central cross-section through the dust box 3000, wherein it is possible to make out, as an enlargement upon figure 6, the disposition of the radially outer folded 5 filter 44 in association with the outer annular wall 3200, and the disposition of an inner folded filter 444 in association with the radially inner annular wall 3900, and wherein the filters 44, 444, which are shaped in a tube-

like manner, force the waste air flowing into the annular 10 compartment 3300 to pass through their filtering surfaces, so that it can be freed from dust and can leave the dust box 3000 towards the outside through the air holes 3900.

Figure 9 shows another exemplified embodiment of a dust box 15 130 in a simplified embodiment in which only the outer annular wall 132 carries air holes 139, which are covered in a leakproof manner by a folded filter 144. In this dust box 130, the central inflow region through the connecting feed-pipe 134 is clear and the waste air flowing in is only 20 able to pass radially outwards through the folded filter 144 and, in the process, to keep the dust in the interior of the dust box 130. The dust box 130, too, carries an end lid 142 which is sealed off axially in relation to the folded filter 144 by means of a seal. As a result, no 25 leakage points can occur between the folded filter 144 and the outer annular wall 132. The air holes 139 are embodied as elongated slots and, to that extent, differ from the round holes in the rest of the exemplified embodiments of the dust boxes. There, the necessity for the rear and 30 front end walls as illustrated in the rest of the exemplified embodiments is eliminated, because the folded filter is able, by reason of the central flowing-in of the waste air at the front, to immediately adjoin the outer end wall of the stepped cylinder 130 between the outer annular 35 wall 139 and the connecting feed-pipe 134, and points of leakage to the air holes 139 can be avoided by suitable

J sealing, which is not represented.

Figure 10 shows a cross-section through the dust box 130 illustrated in figure 9, wherein the folded filter 144 is 5 associated, in a manner folded after the fashion of a meander, with the inner side of the outer annular wall 132.

Since the service life of a filter disposition of this kind in the dust boxes illustrated in the above exemplified 10 embodiments exceeds the service life of the appertaining hand-held machine tool by a multiple, it is possible to dispense with changing the filter in the case of the examples represented.

15 For special cases, it is possible to provide, for the dust boxes, folded-filter cartridges that can be inserted in a replaceable manner in a suitable, appertaining dust box.

Claims

J Claims

1. Hand-held machine tool (10) having a housing (12) to which a dust box (30, 300, 3000, 130) can be detachably 5 fastened, characterized in that the dust box (30, 300, 3000, 130) can be equipped, particularly in a replaceable manner, with an, in particular, rotationally symmetrical filter (44, 440, 4400, 144), in particular a folded filter, which is shaped in a 10 tube-like manner.

2. Hand-held machine tool according to claim 1, characterized in that the dust box (30, 300, 3000, 130) has an outer contour which is adapted to the filter (44, 440, 15 4400, 144).

3. Hand-held machine tool according to claim 1, characterized in that the dust box (30, 300, 3000, 130) is configured as a truncated cone or a cylinder, in particular 20 having an oval cross-section, its rear covering surface being constituted by a removable lid (42, 420, 4200, 142) .

4. Hand-held machine tool according to claim 1, 2 or 3, characterized in that the dust box (130) has a central 25 dust-collecting compartment (133) , the lid (142) constitutes a closed, leakproof wall and the outer annular wall (132) has air holes (139).

5. Hand-held machine tool according to claim 2, 30 characterized in that the dust box (30, 300, 3000, 130) has a central dust-collecting compartment (132) and the lid has air holes.

6. Hand-held machine tool according to claim 2, 35 characterized in that the dust box (30, 300, 3000) has an eccentric dust-collecting compartment (33, 330, 3300) and

the lid (42, 420, 4200) has at least one, in particular central, air hole (43).

7. Hand-held machine tool according to claim 5, 5 characterized in that the eccentric dust-collecting compartment (33, 330, 3300) is configured as an outer annular compartment, and that the lid (42) has a central air outlet hole (43).

10

8. Hand-held machine tool according to claim 2, characterized in that a radially inner, tube-like wall or inner annular wall (38, 380, 3800) of the outer annular compartment (33, 330, 3300) carries a folded filter (44, 440, 4400) and has air holes (39).

9. Hand-held machine tool according to claim 2, characterized in that both the outer annular wall (32, 320, 3200) and also the inner annular wall (38, 380, 3800) of the dust box (30, 300, 3000, 130) have air holes (39) and 20 also carry a folded-filter (44, 440, 4400) which is configured in a tube-like manner.

10. Hand-held machine tool according to one of the preceding claims, characterized in that the dust box 25 (30, 300, 3000, 130) is configured as a stepped cylinder whose region having the smaller cylinder diameter constitutes the inlet feed-pipe (34, 320, 3200) for dust which is being extracted.

30

11. Hand-held machine tool according to claim 5, characterized in that there is disposed centrally in the inner annular wall (38, 380, 3800), a flow cone (26, 260, 2600) whose point is directed towards the air flowing in and directs the latter radially outwards, particularly into 35 the annular compartment (33, 330, 3300).

12. Hand-held machine tool according to claim 8, characterized in that two concentric tubes consisting of folded-filter paper are provided with a plastic corset (50) which spaces apart and centres the tubes, and jointly 5 constitute the filter unit of the dust box (30, 3000, 3000).

13. Hand-held machine tool substantially as herein described with reference to the accompanying drawings.