Abstract:
A hand-held power tool is equipped with a dust extraction device which includes a dust box for holding dust. A closing flap is arranged in a tube section which lies in the flow path to the dust box, and this closing flap can be adjusted between the closed position and the open position. The closing flap is pivotably held in the region of the inner wall of the tube section and can be opened in the direction of the dust box. In the closed position, the closing flap bears against a stop which protrudes into the tube section, extends at an angle with respect to the direction of flow through the tube connection piece, and forms a stop line or stop area against which the closing flap correspondingly bears.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a 35 USC 371 application of PCT/EP2008/057090 filed on Jun. 6, 2008. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a handheld power tool having a dust extractor. 
     2. Description of the Prior Art 
     A handheld power tool of this kind is described in European Patent Disclosure EP 1 171 261 B1. The handheld power tool, designed as an oscillating sander, has a removable dust box in a housing, for receiving the grinding dust that is delivered to the dust box from the tool via a dust guide conduit. In a tubular portion of the dust guide conduit, at the transition to the receiving opening in the dust box, there is a pair of sealing flaps, with which it is intended to be assured that no dust can escape from the dust box back into the dust guide conduit. The pair of sealing flaps comprises a sealing material and is urged by force by its internal stress into a closing position, into which the two sealing flaps rest sealingly on one another and block the flow course. The sealing flaps open in the direction of the dust box, so that even a comparatively slight pressure of the air stream that delivers the sanding dust suffices to open the sealing flaps and open up the flow course into the dust box. In the opposite direction, conversely, the flow course is closed, since at a higher pressure in the dust box, the two sealing flaps are additionally pressed against one another, thus further reinforcing the closing position. 
     OBJECT AND ADVANTAGES OF THE INVENTION 
     The object of the invention is by simple structural provisions to prevent an unwanted return flow of dust from the dust box of a handheld power tool. 
     The handheld power tool according to the invention has a dust box for receiving the dust, and in a tubular portion which is located in the flow course from the tool of the handheld power tool to the dust box, there is at least one adjustable closing flap, which is held pivotably against the inner wall of the tubular portion and is intended to be opened in the direction of the dust box. A stop is disposed in the tubular portion and the closing flap rests on it in the closing position; the stop extends at an angle to the flow direction through the tube stub and forms a stop line or stop area on which the closing flap, in the closing position, rests with an accordingly linear or two-dimensional contact. 
     The linear or two-dimensional stop limits the motion of the closing flap into the closing position, while conversely the opening motion of the closing flap is unimpaired by the stop. In the closing position, the closing flap is in a secured position, so that if there is a reversal of the pressure conditions in the dust box or if other forces such as the rate of the closing flap itself are operative, an opening motion in the opposite direction, which could lead to a return flow of the sanding dust from the dust box back in the direction toward the tool, is reliably prevented. 
     Because of the linear or two-dimensional contact in the closing position, even comparatively soft closing flaps can be used without the risk that the closing flap will be deformed in an unwanted way and cause a flow course back from the dust box to be opened. Soft elastic closing flaps in particular can be used, which are made for instance from a sealing material such as rubber. The linear or two-dimensional contact of the closing flap on the stop stabilizes the closing flap. In addition, the closing flap can be urged in the direction of its closing position by force, in particular by internal stresses in the wall of the closing flap, thereby attaining a self-stabilizing effect. 
     In principle, various embodiments for the stop in the tubular portion can be considered. One possible example is an embodiment as a spring wire, which extends in the tubular portion at the angle to the flow course. The spring wire can at the same time be the holder of the closing flap and in particular can form a joint for pivoting the closing flap open and closed. This joint is embodied for instance as an eyelet-like wire portion of the spring wire that protrudes into a corresponding recess in the closing flap. This eyelet-like wire portion is adjoined on one or both sides by a bearing portion, which is received in a bearing point on the inner wall of the tubular portion. In the spring wire, there is also a middle stop portion, on which the closing flap rests in the closing position. The spring wire has the advantage of being simple to manufacture and easy to machine; in particular, it can be deformed three-dimensionally, and in its stop portion it can for instance extend in two directions in space, so as to form a two-dimensional contact. The bearing point on the inner wall is preferably embodied in one piece with the tubular portion, advantageously as a bearing groove into which the bearing portion of the spring wire is inserted. 
     In another advantageous embodiment, the stop is embodied as a step in the inner wall of the tubular portion. This embodiment has the advantage of not requiring any additional, separate component for the stop; instead, the stop forms an integral component of the inner wall of the tubular portion. 
     The stop extends at an angle to the flow course, and both a disposition perpendicular to the flow course and a disposition extending obliquely can be considered. Particularly in the embodiment of a stop as a step in the inner wall of the tubular portion, an obliquely extending stop can be selected, for opening and closing the closing flap by its own weight, depending on the position of the handheld power tool. In this instance it is recommended that the closing flap and the stop be disposed such that in the usual operating positions of the handheld power tool, the closing flap pivots by its own weight out of the closing position into the opening position, since in the regular operating positions, because of the disposition of the dust box at the bottom and the delivery of dust via an inflow opening at the top, an unintended return flow of sanding dust from the dust box is prevented. Conversely, if the handheld power tool is put into a position in which the accumulated sanding dust could flow back by its own weight via the inflow opening, the closing flap is subjected to a closing moment by the force of gravity, so that the flow course back to the tool is closed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further advantages and expedient embodiments can be learned from the detailed description below in conjunction with the drawings, in which: 
         FIG. 1  is a section through a handheld power tool according to the invention, embodied as a power drill, which in its lower housing region is provided with a dust box; 
         FIG. 2  is an enlarged detail of the region of the closing flap; 
         FIG. 3  is a perspective view of the tube elbow in a view from below; 
         FIG. 4  is a further illustration of the tube elbow, with the spring wire inserted into the bearing point; 
         FIG. 5  is a further illustration of the tube elbow, with additionally inserted closing flaps; 
         FIG. 6  is a section through the tube wall of the tube elbow in the region of the bearing points that receive the spring wire; 
         FIGS. 7 through 9  show various views of the spring wire; 
         FIGS. 10 through 12  show various views of a closing flap; 
         FIGS. 13 and 14  show two perspective views of two closing flaps mounted on the spring wire; 
         FIG. 15  is a schematic illustration of a tubular portion with two integrated closing flaps and with a spring wire that forms the stop; 
         FIG. 16  is a schematic illustration of a tubular portion with integrated closing flaps in a further embodiment, in which the two closing flaps are urged into the opening position via elastic threads secured to the inner wall; 
         FIG. 17  shows a tube elbow as part of the flow course for the exhaust air containing the drilling dust, with an integrated closing flap which in the closing position rests on a stop that is embodied as a step in the inner wall of the elbow; 
         FIG. 18  is a view of the tube elbow, including the step that fog ins the stop; 
         FIG. 19  shows the closing flap individually. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In  FIG. 1 , what is shown of the power drill  1  in detail is the dust extractor  2 , which includes a suction head  3 , a suction tube  5 , a tube elbow  6 , and a dust box  7 . The suction head  3  is located adjacent to the rotating tool, not shown, and is disposed coaxially to the drill axis  4 . The exhaust air stream, generated with the aid of a ventilator or the like and carrying the dust particles, is conducted via the suction tube  5  and tube elbow  6  into the dust box  7 , which is located in the lower part of the housing  8  of the power tool. The tube elbow  6 , which connects the suction tube  5  to the dust box  7 , may be a fixed component of the suction tube  5 , but an embodiment as a separate component can optionally be considered, and it discharges into an inflow opening  9  located at the top (see  FIG. 2 ) in the wall of the dust box  7 . The air stream is carried out of the dust box  7  via an outlet opening  10 , in which a filter element is advantageously disposed. 
     As can be seen from  FIG. 1  in conjunction with the enlarged view in  FIG. 2 , in the region of the face end of the tube elbow  6 , on the side toward the inflow opening  9 , a closing flap  11  is integrated with the tube elbow and is intended to be adjusted between a closing position that blocks the flow course and an opening position that opens the flow course. The closing flap  11  is held on a spring wire  12 , which is secured in bearing points disposed on the inner wall of the tube elbow  6 . The spring wire  12  has an eyelet-like wire portion  12   a , which forms the bearing for the pivotability of the closing flap  11 . A middle portion  12   b  of the spring wire  12  forms a stop for the closing flap  11 , on which the closing flap rests in the closing position. In the opening position, the closing flap pivots out of its contact with the stop portion  12   b  in the direction of the interior of the dust box  7 . In this way it is assured that the closing flap  11  can open in the direction of the dust box  7  under the pressure of the air stream delivered that contains the dust particles, while conversely in the opposite direction, opening of the closing flap is effectively precluded because of the stop. The opening of the closing flap  11  is effected by elastically bending open the closing flap wall. 
     In  FIGS. 3 through 5 , various steps in assembling the tube elbow  6  and the integration of the closing flap  11  are shown.  FIG. 3  first shows the view of the face end  13  of the tube elbow  6 , which end protrudes past the inflow opening in the wall of the dust box, before the closing flap is installed. On the inner wall of the tube elbow  6 , adjacent to the face end  13 , there is a bearing point  14 , which comprises two wall portions, embodied in one piece with the inner wall, protruding transversely to the flow direction, and spaced apart axially from one another, between which wall portions a receiving groove  15  is formed, which serves to receive a bearing portion of the spring wire  12 . 
     The installed situation with the spring wire inserted into the groove  15  is shown in  FIG. 4 . For reasons of symmetry, on each of the opposed inner sides of the wall of the tube elbow there are respective bearing points  14 , each with a receiving groove  15  into each of which one bearing portion of the spring wire  12  is introduced. The eyelet-like wire portion  12   a  of the spring wire  12 , in the installed position, is located adjacent to and approximately parallel to the inner wall of the tube elbow  6 . In the region of the face end  13 , the tube elbow has an approximately rectangular cross section, and the eyelet-like wire portions  12   a  and the bearing points  14  are located on the short side of the rectangle. 
     In  FIG. 5 , finally, the installed position is shown, with integrated closing flaps  11 . Two closing flaps are provided, which are each pivotably supported on an eyelet-like wire portion  12   a  on opposed inner wall sides of the tube elbow  6 . The two closing flaps  11  are disposed mirror-symmetrically to one another and in the closing position rest on their face ends against one another. However, an overlapping closing position can optionally be considered as well. 
     From the sectional view of the tube elbow  6  in  FIG. 6 , the bearing points  14 , positioned on opposed inner wall sides of the tube elbow adjacent to the face end  13 , can be seen, with the two wall portions protruding transversely into the flow course and with a receiving groove  15  between them. 
     In  FIGS. 7 through 9 , the spring wire  12  is shown in various views, of which  FIG. 7  shows a perspective view,  FIG. 8  a top view, and  FIG. 9  a side view. The spring wire  12  is bent three-dimensionally and in each of its outer regions it has a respective eyelet-like wire portion  12   a , which in the installed position ( FIG. 4 ) is located parallel to the inner wall, while conversely, a middle stop portion  12   b , connecting the two eyelet-like wire portions  12   a  to one another, is located in a plane that is perpendicular to the plane that receives the eyelet-like wire portions  12   a . The stop portion  12   b  extends with various segments in both directions of the stop plane. Furthermore, bearing portions  12   c  are provided, which are disposed on both sides of the eyelet-like wire portions  12   a  and are received in the receiving groove  15  of the bearing point  14  ( FIG. 6 ) on the inner wall of the tube stub. The eyelet-like wire portion  12   a  forms a holder for the closing flap that in the closing position rests on the middle stop portion  12   b.    
     In  FIGS. 10 through 12 , various views of the closing flap  11  are shown;  FIG. 10  is a first perspective view from above,  FIG. 11  a top view, and  FIG. 12  a second perspective view from below. The closing flap  11  comprises a bearing portion  16 , into which a recess  17  is made for receiving the eyelet-like wire portion  12   a  of the spring wire  12 , and a closing part  19  of slight wall thickness, which performs the actual closing function. The closing flap  11  is expediently made from a soft elastic material, such as rubber. The bearing portion  16  of the closing part  19  are embodied in one piece with one another, and between the thin-walled closing part  19  and the relatively thick bearing portion  16 , respective lateral notches  18  are made, which enable and reinforce a relative pivoting motion of the closing part  19  with respect to the bearing portion  16 . The two diametrically opposed notches  18  thus define a pivot axis  20  for the closing part  19 , so that the closing part can be pivoted between the closing and opening positions. 
     In  FIGS. 13 and 14 , two closing flaps  11  each are shown in the mounted position on the spring wire  12 , in views from above ( FIG. 13 ) and below ( FIG. 14 ) in the closing position. The underside of the closing part  19 , in the closing position, rests on the stop portion  12   b  of the spring wire  12  in linear fashion, and because of the length of the stop portion  12   b , effective bracing is provided in two directions of the stop plane. 
     In  FIG. 15 , a schematic view of the tubular portion  6  is shown, with two integrated closing flaps  11 , which are pivotably supported on opposed inner sides of the wall of the tubular portion and can brace themselves on the spring wire  12  in the closing position. In the opening position, shown, the closing flaps  11  are pivoted about their joint near the wall and open the flow course in the direction of the dust box. 
     In  FIG. 16 , a further exemplary embodiment of a tubular portion  6  is shown, with two integrated closing flaps  11 . The closing flaps  11  are each held in the opening position via an elastic thread  21 , which is secured on one end to the inner wall of the tubular portion and on the other to the free face end of the closing flap. Upon a flow reversal, the closing flaps  11  can assume their closing position because of the elasticity of the threads  21 , so that a return flow of air laden with dust particles from the dust box is prevented. 
     In  FIGS. 17 through 19 , a further exemplary embodiment of a tube elbow, with a single integrated closing flap, is shown. The tube elbow  6  has a bearing point  14  on only one inner side of the wall, and this bearing point is embodied as a cylindrical recess in the wall of the tube elbow and is embodied for receiving the bearing portion  16  at the closing flap  11 . This bearing portion  16 , as can be seen from  FIG. 19 , is adapted to the cross section of the recess in the bearing point  14 ; both the recess in the bearing point  14  and the bearing portion  16  have a cross section that is only part of a circle, so that a rotation of the bearing portion  16  of the closing flap  11  in the recess of the bearing point  14  is not possible. The pivotability of the closing flap  11  is on the contrary formed by a tapered wall portion  19   a  ( FIG. 19 ), by way of which the closing part  19  of the closing flap  11  is joined to the bearing portion  16 . 
     In the closing position, which is shown in  FIG. 17 , the closing flap  11  rests on a step  22 , which is made into the inner side of the wall of the tube elbow  6  and extends obliquely to the flow direction through the tube elbow from one inner side of the wall to the opposite inner side of the wall. The step  22  has an angled portion, so that in the closing position, the closing flap  11  rests on the step  22  via a total of two stop lines. 
     For reinforcing the closing flap  11  that is made from soft elastic material, reinforcing ribs  23  may be disposed in the region of the closing part  19 , as shown in  FIG. 19 . From this drawing it can also be seen that a mounting cam  24  is disposed on the bearing portion  16 ; it, is intended to prevent the bearing portion  16  from being mounted incorrectly in the recess of the bearing point  14 . 
     The foregoing relates to the preferred exemplary embodiments of the invention, it being understood that other variants and embodiments thereof are possible within the spirit and scope of the invention, the latter being defined by the appended claims.