Abstract:
A dust removal system handheld power tool includes a fan ( 18 ) to generate an air flow ( 19 ), a suction nozzle ( 27 ) to capture dust-laden air from a tool ( 4 ), and a collecting container ( 22 ) to collect the dust. The collecting container ( 22 ) has a suction opening ( 27 ) connected to the suction nozzle ( 27 ) as well as an exhaust opening ( 28 ) connected to the fan ( 18 ). A filter ( 29 ) serves to separate dust into the collecting container ( 22 ) and is arranged so as to cover the exhaust opening ( 28 ). The filter ( 29 ) has several consecutive fins ( 18 ) arranged one beside the other in a direction (y) that is perpendicular to the direction (z) of the air flow ( 19 ). The fins ( 18 ) are slanted with respect to each other. The slant ( 42 ) of the fins ( 44 ) reduces the adhesion of the dust to the fins ( 44 ).

Description:
[0001]    The present invention relates to a dust removal system for a handheld power tool. 
       BACKGROUND 
       [0002]    A dust removal system of the generic type is disclosed, for example, in German patent application DE 10 2010 040094 A1. The dust filter needs to be replaced often since it becomes clogged with dust. 
       SUMMARY OF THE INVENTION 
       [0003]    The present invention provides a dust removal system for a handheld power tool having a fan to generate an air flow, a suction nozzle to capture dust-laden air from a tool, and a collecting container to collect the dust. The collecting container has a suction opening connected to the suction nozzle as well as an exhaust opening connected to the fan. A filter to separate dust into the collecting container is arranged so as to cover the exhaust opening. The filter has several consecutive fins arranged one beside the other in a direction (y) that is perpendicular to the direction (z) of the air flow. The fins are slanted towards each other. The slant of the fins reduces the adhesion of the dust to the fins. 
         [0004]    One embodiment provides for the outermost fins to be slanted towards each other by 3° to 10°. The adjacent fins are supposed to be slanted towards each other. A slant of more than 10° appears to be sufficient. A greater slant causes not only a loss in performance but also requires more space. 
         [0005]    One embodiment provides for the fins to be attached in a frame that can be bent in the direction (z) of the air flow and for the frame to be placed onto a pedestal that is convexly elevated opposite to the direction (z). 
         [0006]    One embodiment provides for the end face of the filter that is exposed to the flow to be less than 10% larger than an end face of the filter facing away from the flow. The fan has to build up a pressure differential of several mbars relative to the suction nozzle. Since only a small motor can be employed for handheld devices, pressure losses should be avoided under all circumstances. Consequently, a cuboidal or virtually cuboidal structure is a must. 
         [0007]    One embodiment provides for the pedestal to have a guide slanted in the direction (z) of the air flow, whereby one of the fins is placed onto said guide. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The description below explains the invention on the basis of embodiments and figures given by way of examples. The figures show the following: 
           [0009]      FIG. 1 : a hammer drill with a dust removal system; 
           [0010]      FIG. 2 : a sectional view through the dust removal system in the plane II-II; 
           [0011]      FIG. 3 : a top view of a filter; 
           [0012]      FIG. 4 : a sectional view through the dust removal system in the plane IV-IV; 
           [0013]      FIG. 5 : a sectional view through a dust removal system in the plane II-II; 
           [0014]      FIG. 6 : a sectional view through another dust removal system in the plane II-II; 
           [0015]      FIG. 7 : a top view of the filter from  FIG. 6 . 
       
    
    
       [0016]    Unless otherwise indicated, identical or functionally equivalent elements are designated in the figures with the same reference numerals. 
       DETAILED DESCRIPTION 
       [0017]      FIG. 1  shows a dust removal system  1  that is placed onto a hammer drill  2 . By means of a chiseling drill bit  3 , the hammer drill  2  creates holes in rock, concrete, etc. The dust removal system  1  captures the generated drill cuttings, particularly the fine dust, from the drilled hole. 
         [0018]    The drill hammer  2  given by way of an example has a tool socket  4  into which the drill bit  3  can be inserted and locked in place. The tool socket  4  is coupled by a rotary drive  5  to a motor  6  that drives the tool socket  4  so that it rotates around a working axis  7 . A pneumatic striking mechanism can strike the drill bit  3  along the working axis  7  in the working direction  8 . The striking mechanism is likewise driven by the motor  6 . The motor  6  drives an eccentric cam  9  that forces an exciter piston  10  to make a periodic back-and-forth movement. A striker  11  is coupled to the movement of the exciter piston  10  via an air cushion  12 . The drive components are arranged in a machine housing  13 . A handle  14  for holding and guiding the hammer drill  2  during operation can be attached to the machine housing  14 , either rigidly or with damping. The user can start the motor  5  by means of a main switch  15 . 
         [0019]    The dust removal system  1  has a housing  16  with a holder  17 . The user can attach the dust removal system  1  to the hammer drill  2  by means of the holder  17 . The holder  17  comprises a movable journal, a pawl, a clamp, etc. 
         [0020]    The dust removal system  1  has a fan  18  that generates an air flow  19 . The housing  18  given by way of an example has an impeller  20  and an electric motor  21  that drives the impeller  20 . The impeller  20  draws in air in the radial direction and blows the air out in the axial direction through appropriate openings in the housing  22 . 
         [0021]    A suction nozzle  23  of the dust removal system  1  is arranged in the direct vicinity of the drill bit  3 . The suction nozzle  23  can have, for instance, a sleeve  24  that surrounds the drill bit  3 . The sleeve  24  given by way of an example has a sealing gasket  25  that comes into contact with the drill bit  3 . In the specific drill bit  3  shown here, the drill cuttings are drawn in inside the shank of the drill bit  3 . In the case of conventional drill bits with a transport screw, the suction nozzle  23  preferably likewise surrounds the drill bit and, at the same time, is in contact with the workpiece. 
         [0022]    The dust-laden air captured by the suction nozzle  23  is transported by the air flow  19  into a collecting container  22 . The suction nozzle  23  is connected to a suction opening  27  of the collecting container  22  via a tube  26 , a rigid pipe, a telescopic pipe or some other tubular conduit. The collecting container  22  has a flat outlet opening  28  that is completely covered by a filter  29 . The fan  18  is situated downstream from the filter  29 . The dust in the air flow  19  is separated at the filter  29  and is left behind in the collecting container  22 . The air flow  19  that reaches the fan  18  is free of dust. The housing  30  of the collecting container  22  is configured so as to be air-tight so that the entire air flow  19  that enters via the suction opening  27  only exits via the outlet opening  28 . 
         [0023]      FIG. 2  shows the installed filter  29  given by way of an example, in a cross sectional view in the plane II-II.  FIG. 3  shows a top view of the end face  31  of the filter  29  that is exposed to the flow. The filter  29  has an essentially cuboidal structure. The dimensions of the cube will be designated below as is usually done, namely, length  32 , width  33  and height  34 , while the appertaining axes are designated as the x-axis, y-axis and z-axis. An end face  31  that is exposed to the flow where the dust accumulates as well as an end face  35  facing away from the flow which remains virtually clean are positioned perpendicular to the z-axis and are essentially of the same size. The end faces  31 ,  35  equal the product of the length  32  and the width  33  of the filter  29 . The deviation is less than 10%. These equal dimensions prevent a pressure drop. 
         [0024]    The filter  29  has membrane  36  whose surface through which the flow passes is several times greater than the end faces  31 ,  35 . The membrane  36  is made up of a plurality of fins  37 , preferably all having the same design. The fins  37  consist essentially of two opposing flat sides  38 . The sides  38  are made up of the permeable membrane  36 , which has a pore size configured to capture the dust. The sides  38  are separated from each other by a thin conduit  39  that is configured so as to be flat. Dust-laden air can penetrate through the sides  38  while leaving the dust behind and the air can subsequently flow away in the conduit  39  between the sides  38 . The sides  38  are preferably of the same size. The sides  38  are preferably either parallel to each other or else slanted with respect to each other by a small angle, less than 5°. The sides  38  are connected to each other at a head line  40 . Adjacent fins  37  are each joined to each other by a foot line  41  of the sides  38 . 
         [0025]    The fins  37  are oriented parallel to each other relative to the x-axis, that is to say, the sides  38 , the head lines  40  and the foot lines  41  are parallel to each other. The fins  37  are consecutive to each other in the y-direction, preferably without partially overlapping in this direction. The fins  37  are slanted at a small angle with respect to the z-axis, which will be elaborated upon below. The head lines  40  of the fins  37  face opposite to the air flow  19 . 
         [0026]    The fins  37  are oriented in a fanned pattern. The fins  37  are slanted towards each other. The slant  42  between the fins  37  is determined between the gravitational planes of their sides  38 , or equivalently, the slant  42  is determined between the appertaining sides  38  that face in the same direction. The distance  43  between adjacent fins  37  decreases in the direction of the air flow  19 . The slant  42  is not equal to zero between all adjacent fins  37 , preferably, it is of the same magnitude. The two outermost fins  44  along the y-axis have a relative slant  42  within the range from 3° and 10°. Consequently, the flow comes in essentially from an axial direction. 
         [0027]    The membrane  36  consists of a sheet of pleated paper or a pleated textile. The pores of the membrane  36  can advantageously have a mean size of less than 5 μm in order to capture dust. The sheet is folded several times in alternating opposite folding directions along fold lines that run parallel to the x-axis. The first side surface  38  of the fins results from a pleat in the folding direction while the second side  45  is the next pleat in the opposite direction. The two sides  38 ,  45  are joined along the fold line, which forms the head line  40  and, by the same token, the adjacent fins  37  are joined along a fold line that forms the foot line  41 . The distance between the sides  38  of a fin  37  is smaller than the distance between two adjacent fins  37 . 
         [0028]    The filter  29  has a frame  46 . The frame  46  joins the foot lines  41  along the y-axis. The membrane  36  cannot unfold any further. The height of the frame  46  is preferably considerably smaller than the height  34  of the pleated membrane  36 . The edges  40  facing the flow are not fixed in the frame  46 , but rather, they are movable. The preferred frame  46  is made of a flexible synthetic material, for example, rubber. 
         [0029]    The outlet opening  28  of the collecting container  22  is covered by the filter  29 . The outlet opening  28  has a frame-shaped pedestal  47  that surrounds the outlet opening  28 . The frame  46  of the filter  29  rests against the pedestal  47  with a positive fit in order to prevent leaks. The frame-shaped pedestal  47  has first areas  48  that run along the x-axis, in other words, along the edges  40 ,  41  of the fins  44 , and second areas  49  that run along the y-axis, in other words, essentially perpendicular to the fins  44 . The first areas  48  are essentially rectilinear and formed so as to lie in a plane. The second areas  49  are concavely curved along the y-axis. The second area  49  is closer to the inside of the collecting container  22  in the center than at the edge ( FIG. 4 ). The flexible frame  46  of the filter  29  that is pressed against the pedestal  47  is correspondingly deformed. Therefore, the edges  41  facing away from the flow are at different heights along the z-axis. The pleated membrane  36  spreads open in a fanned pattern; the fins  37  acquire the slant  42  relative to each other. 
         [0030]    The housing  16  of the dust removal system  1  has a pedestal  50  that is opposite from the pedestal  47  of the collecting container  22 . The frame  46  of the filter  29  is clamped between the two pedestals  47 ,  50 . The pedestal  50  of the housing  22  has a convex section along the y-axis that is preferably complementary to the second area  49  of the pedestal  47  of the collecting container  22 . In one embodiment, only the housing  22  is provided with a convexly curved pedestal  50 . 
         [0031]      FIG. 5  shows another embodiment. The housing  22  is provided with guide plates  51 . The guide plates  51  are slanted relative to the z-axis, equal to the slant  42  of the outermost fin or outer fins  44 . The outer fins  44  with the conduit  39  are placed onto the guide plates  51 . The guide plates  51  effectuate or assist the fan-like spreading of the membrane  36  consisting of the fins  37 . A guide on the side facing away from the flow proves to be advantageous since the guide  51  does not offer any seed point for the accumulation of dust. 
         [0032]      FIGS. 6 and 7  show another embodiment. The fins  37  are provided with spacers  52 . The spacers  52  are arranged on the head line  40 . The spacers  52  have a dimension along the y-axis that is greater than the distance of the foot line  41 . As a result, the head lines  40  are further apart from each other than the foot lines  41  in order to attain the desired fan-like spread. The spacers  52  can be placed onto the head lines  40  as an add-on. Preferably, the spacers  52  are embossed into the membrane  36  before the membrane  36  is pleated to form the fins  37 .