Abstract:
The dust removal device comprises a fan ( 18 ), a dust collection receptacle ( 24 ), and a suction passage ( 28 ). The dust collection receptacle ( 24 ) equipped with a dust filter ( 26 ) is located in the path of air flow ( 34, 36 ) between the suction passage ( 28 ) and the fan ( 18 ). The dust is therefore filtered out of the air stream before it reaches the fan, which prevents dust-induced wear. It is also possible to use the same fan for engine cooling as well as dust removal.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention concerns a hand power tool with a dust removal device, comprising a fan driven by the motor of the hand power tool, a dust collection receptacle, and a suction passage, whereby a path of air flow exists between the fan, the suction passage, and the dust collection receptacle such that air is drawn through the suction passage by the fan, and the dust particles present in the suctioned air flow are conveyed into the dust collection receptacle.  
           [0002]    A hand power tool with a dust removal device of this type was made known in DE 196 53 330 A1. The fan of this known dust removal device draws the air filled with dust particles through the suction passage and then blows it into a dust collection receptacle. The air filled with dust particles is therefore drawn through the fan. This has the disadvantage that the fan can be damaged by the dust, which comes in at a relatively high rate of speed.  
           [0003]    The invention is based on the object of providing a hand power tool with a dust removal device of the type stated initially that can be realized with the least amount of technical effort possible, and that is as wear-resistant as possible.  
         ADVANTAGES OF THE INVENTION  
         [0004]    The stated object is attained with the features of claim 1 by locating the dust collection receptacle equipped with a dust filter in the path of air flow between the suction passage and the fan of the dust removal device. In this fashion, the air filled with dust particles is not drawn through the fan, as with the related art. Instead, the dust particles are filtered out in the dust collection receptacle before the suctioned air reaches the fan. This prevents wear on the fan induced by dust. Advantageous further developments of the invention result from the dependent claims.  
           [0005]    A particular advantage has proven to be the fact that a further path of air flow exists between the fan and the motor, so that the fan brings about a cooling of the motor simultaneously with and in addition to dust removal. Two different functions can therefore be realized with very little technical expense and in a compact design.  
           [0006]    The path of air flow provided to cool the motor can be formed in two different ways. Either air is drawn in by the fan from outside the hand power tool and is directed past the motor before it reaches the fan, or the fan blows the air out past the motor that was drawn in through the suction passage and the dust collection receptacle.  
           [0007]    It is advantageous to provide an air passage for the fan that supplies air to the fan when the fan produces an increased vacuum caused by the dust filter becoming clogged. With this additional air passage, the motor can still be cooled if the dust filter becomes clogged. 
       
    
    
     SUMMARY OF THE DRAWINGS  
       [0008]    The invention will be described hereinbelow with reference to the exemplary embodiments presented in the drawings.  
         [0009]    [0009]FIG. 1 is a partial sectional view of a hand power tool with a first variant of a path of air flow that cools the motor,  
         [0010]    [0010]FIG. 2 is a schematic representation of the mode of action of dust removal and motor cooling according to the variant according to FIG. 1,  
         [0011]    [0011]FIG. 3 is a partial sectional view of a hand power tool with a second variant of a path of air flow to cool the motor, and  
         [0012]    [0012]FIG. 4 is a schematic representation of the mode of action of dust removal and engine cooling according to the variant depicted in FIG. 1. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0013]    [0013]FIG. 1 is a partial sectional view of a hand power tool  10 , e.g., a drilling hammer. The invention described hereinbelow concerns any type of hand power tool, however, that has a rotating drive and with which dust is produced when an object is machined.  
         [0014]    As one can see through the cut-out in FIG. 1, a motor  12  is located in the hand power tool  10  that has a drive shaft  14  for a tool (not shown) mounted in a tool holder  16  of the hand power tool  10 . A fan  18  is mounted on the drive shaft  14  that comprises a fan chamber  20  and a ventilator  22  that is located therein and is coupled with the drive shaft  14 .  
         [0015]    A dust collection receptacle  24  with a dust bag  26  functioning as dust filter is located on the outside of the power tool  10 . A suction passage  28  empties into the dust collection receptacle  24  and/or into the dust bag  26 , which said suction passage extends into the vicinity of the tool mounted in the hand power tool  10  where dust is produced while the hand power tool  10  is operated. An air-conducting connection is produced between the dust collection receptacle  24  and the ventilator  22  of the fan  18  via a common opening  30  in the dust collection receptacle  24  and in the housing of the hand power tool  10 , and via an opening  32  in the fan chamber  20  of the fan  18 . A path of air flow is therefore produced to the fan chamber  20  via the suction passage  28  and the dust collection receptacle  24  equipped with a filter  26 .  
         [0016]    If the ventilator  22  is now started rotating when the hand power tool  10  is operated and a vacuum is therefore produced in the fan chamber  20 , the air filled with dust and generated at the site of the tool is drawn in through the suction passage  28  and into the dust collection receptacle  24 , as indicated by the dashed arrow  34 . The air flow passes through the dust bag  26 , by way of which it is separated from the dust particles, and finally reaches the fan chamber  20 , as indicated by the dashed arrow  36 . The suctioned air is blown out of the fan chamber  20  through an opening  38  in another side of the fan chamber  20 —as indicated by the dashed arrow  40 —and reaches the outside through one or more air slits  42  in the housing of the hand power tool  10 .  
         [0017]    In addition, an air stream directed past the motor  12 —as indicated by the dashed arrow  46 —is drawn in through one or more openings  32 ,  44  in the fan chamber  20 , which said openings face the motor  12 . This air stream  46  is drawn in from the outside through one or more air slits  48  in the housing wall of the hand power tool  10 . The air slit or air slits  48  is/are positioned relative to the motor  12  in such a fashion that a path for air flow past the motor  12  results that ensures optimum cooling of the motor  12 . The air drawn in past the motor  12  is also blown out of the fan chamber  20  to the outside via one or more openings  38  in the opposite side of the fan chamber  20  through the air slit(s)  42  in the housing wall of the hand power tool  10 . The fan  18  therefore performs two functions simultaneously, i.e., dust removal and motor cooling.  
         [0018]    The ventilator  22  in the fan chamber  20  can be installed directly on the drive shaft  14  of the motor  12 , or it can be coupled with the drive shaft via a gearset having a high gear ratio. The ventilator  22  could therefore be operated at a high rotational speed in order to obtain the greatest suction power possible. The suction power can also be increased by situating a plurality of ventilators in tandem.  
         [0019]    In deviation from the exemplary embodiment presented in FIG. 1, in the case of which the dust collection receptacle  24  is located outside the hand power tool  10 , this dust collection receptacle can also be integrated inside the hand power tool  10 .  
         [0020]    Passages having an appropriate structural design can be provided inside the hand power tool to obtain a more targeted conductance of the air flows  36 ,  40 ,  46  and, therefore, a more effective intake and/or discharge of air.  
         [0021]    The schematic representation shown in FIG. 2 is provided to illustrate the individual paths of air flow that occur in the hand power tool  10  according to FIG. 1. The individual blocks  12 ,  18 ,  24  represent the motor  12 , the fan  18 , and the dust collection receptacle  24  with the dust bag  26  located therein and serving as filter. The air flows  34 ,  36 ,  42 ,  46  drawn in FIG. 1 have the same reference numerals in FIG. 2. FIG. 2 shows clearly that two paths of air flow  36  and  46  enter the fan  18 , whereby the one path of air flow  36  travels through the dust collection receptacle  24 , and the other path of air flow  46  travels past the motor  12 .  
         [0022]    [0022]FIGS. 3 and 4 show a further exemplary embodiment of a dust removal device that performs motor cooling simultaneously with and in addition to dust removal. The elements in FIGS. 3 and 4 that have the same significance and mode of action as elements in FIGS. 1 and 2 have been labelled with the same reference numerals as in FIGS. 1 and 2. Elements that are found in FIGS. 1 and 2 and that were already described hereinabove will not be described once more with regard for FIGS. 3 and 4. The exemplary embodiment presented in FIGS. 3 and 4 basically differs from the exemplary embodiment in FIGS. 1 and 2 in terms of a different path of air flow for cooling the motor  12 .  
         [0023]    The air flow that was drawn in via the suction passage  28  and cleaned of dust by the dust bag  26  acting as filter travels through one or more openings  50  and reaches the fan chamber  20 . The air is blown out of the fan chamber  20  through one or more openings  32 ,  44  in such a manner, in fact, that this discharged air is directed past the motor  12  and travels through one or more air slits  48  in the housing wall of the hand power tool  10  to reach the outside. This air stream, which leaves the fan chamber  20  and serves to cool the motor  12 , is indicated in FIG. 3 by a dashed arrow  52 . In order to convert the suctioned air flow  36  into the cooling air flow  52 , the opening  50  is located on the side of the fan chamber  20  opposite the motor  12  and the openings  32 ,  44 .  
         [0024]    The dust bag  26  can become so full of dust that the air flow  36  drawn in by the fan  18  is not sufficient to form a cooling air flow  52  that is great enough for the motor  12 . An additional air passage  54  is provided for this case, which said additional air passage empties into the fan chamber  20  via an opening  56 . This opening  56  for the air passage  54  is located on the same side as the opening  50  for the air flow  36  from the dust collection receptacle  24 . The air passage  54  leads out of the housing of the hand power tool  10  and forms an access for an air flow  58 , shown as a dashed arrow, from outside of the hand power tool  10  into the fan chamber  20 . The air flow  58  into the fan chamber  20  should not be opened, however, until the other air flow  36  out of the dust collection receptacle  24  has become too weak, which is expressed as an increase in the vacuum in the fan chamber  20 . A valve  60  is therefore provided in the air passage  54  that does not open and allow air  58  to be drawn in until an increased vacuum occurs in the fan chamber  20 . In this fashion, adequate cooling of the motor  12  is possible even when the dust filter is clogged.  
         [0025]    The dual function of the fan  18 , i.e., dust removal and motor cooling, can be illustrated once more with reference to the schematic illustration in FIG. 4. The same reference numerals are used in FIG. 4 as for the corresponding elements and air flows shown in FIG. 3. FIG. 4 illustrates that the air flow  36 —directed through the dust collection receptacle  24  and cleaned of dust—is converted into an air flow  52  to cool the motor  12 . The air flow  58  controlled by the valve  60  is also indicated in FIG. 4, which said air flow supplements or replaces the air flow  36  from the dust collection receptacle  24  when a certain vacuum occurs in the fan chamber  20  that is caused by the dust bag  26  becoming clogged.