Abstract:
The invention is based on a dust and chip removal device, in particular for sanding hand power tools ( 10 ), having a transport channel ( 12, 14 ), via which the dust and chips can be directed into a storage container ( 16 ) secured to the hand power tool ( 10 ) in particular, and having a dust and chip retaining device that comprises a retaining element ( 18, 20, 22, 24 ) to prevent the dust and chips from flowing back out of the storage container ( 16 ).  
     It is proposed that the retaining element ( 18, 20, 22, 24 ) comprises at least one passage ( 28, 30, 32, 34 ) that is closed by means of a holding force of an elastic element, and the passage ( 28, 30, 32, 34 ) opens automatically against the holding force starting at a certain delivery pressure, and the elastic element automatically closes the passage ( 28, 30, 32, 34 ) below a certain delivery pressure.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The invention is based on a dust and chip removal device, with a dust and chip retaining device, according to the preamble of claim  1 .  
           [0002]    The use of power tools to draw off dust and chips from a working surface using a suction device and moving it through a transport channel into a storage container, e.g., into cloth dust bags or paper filters, is known.  
           [0003]    To prevent the dust and chips from flowing back out of the storage container when the power tool is switched off, it is known to provide a dust and chip retaining device that comprises a manually operated retaining flap. An operator can manually close and open the storage container via the retaining flap.  
         ADVANTAGES OF THE INVENTION  
         [0004]    The invention is based on a dust and chip removal device, in particular for sanding hand power tools, having a transport channel, via which the dust and chips can be directed into a storage container secured to the hand power tool in particular, and having a dust and chip retaining device that comprises a retaining element to prevent the dust and chips from flowing back out of the storage container.  
           [0005]    It is proposed that the retaining element comprises at least one passage that is closed by means of a holding force of an elastic element, and the passage opens automatically against the holding force starting at a certain delivery pressure, and the elastic element automatically closes the passage below a certain delivery pressure. Backflow of the dust and chips when the machine is switched off, and having the storage container accidentally closed during operation of the machine can be reliably prevented.  
           [0006]    The holding force can be produced by means of a separate spring element, but the retaining element is advantageously made of a soft-elastic material, and the retaining element and the elastic element are designed as a single component, by way of which additional components, installation space, weight, assembly expense and costs can be spared.  
           [0007]    If a channel has cross-sectional area that tapers toward the passage, and/or if the channel is designed in the shape of a nozzle, an advantageous opening behavior can be obtained with just a small amount of delivery pressure, and an increased particulate speed can be obtained in the region of the passage, by way of which a cleaning of the storage container in an anterior part closest to the passage and an advantageous filling of the storage container from the rear in the direction of the passage can be obtained.  
           [0008]    The channel could basically be formed by a part of the machine or a part of the storage container. If the channel is formed by the retaining element, however, said retaining element can be used advantageously with a plurality of storage containers that can be produced cost-effectively, e.g., storage containers made of paper, and/or they can be used with multiple machines. With a channel formed by the retaining element and extending into the storage container, it can be further achieved that the weight of the dust and/or chips assists the elastic element in closing the passage when the machine is switched off and prevents the dust and/or chips from flowing back. This is accomplished in that the dust and/or chips act on the possibly elastically designed walls of the channel in the closing direction when the machine is switched off.  
           [0009]    Instead of channel walls extending in the transport direction and toward each other toward the center, the tapering can also be produced advantageously by means of a protrusion extending against the transport direction. A reduction of the volume of the storage container caused by the tapering channel can be prevented, and a large volume in the storage container can be obtained.  
           [0010]    In a further embodiment of the invention it is proposed that at least one wall of the tapering channel extends along an exponential function in the transport direction, by way of which advantageous flow conditions and an advantageous opening behavior can be obtained even when a small amount of delivery pressure is applied. Moreover, when the wall thickness of the retaining element decreases as it nears the passage, e.g., advantageously according to an exponential function, this has an advantageous effect on the opening behavior, especially when delivery pressures are low.  
           [0011]    The passage can be formed by various embodiments appearing reasonable to one skilled in the art, e.g., by one or more incisions in a soft-elastic wall of the retaining element. If the passage is formed by at least two intersecting incisions, a large passage opening can be obtained in simple fashion.  
           [0012]    It is further proposed that at least one seal and/or a support piece is integrally molded on the retaining element, by way of which additional components, weight and assembly expense can be spared.  
           [0013]    The means of attaining the object according to the invention can be used with various devices appearing reasonable to one skilled in the art, but particularly advantageously with sanding hand power tools, such as hand-guided oscillating sanders, disk-type sanders, etc., with which fine chips and/or sanding dust are produced. Sanding dust and/or fine chips can be accelerated particularly advantageously via the nozzle-shaped channel and directed through the passage into a rear section of the storage container. Moreover, the means of attaining the solution according to the invention are used particularly advantageously with storage containers secured to the hand power tool that are moved into various positions with the hand power tool, and even into positions in which the dust and chips would flow back into the hand power tool out of the storage container when the hand power tool is switched off. 
       
    
    
     SUMMARY OF THE DRAWINGS  
       [0014]    Further advantages result from the following description of the drawing. Exemplary embodiments of the invention are presented in the drawings. The drawings, the description, and the claims contain numerous features in combination. One skilled in the art will advantageously consider them individually as well and combine them into reasonable further combinations.  
         [0015]    [0015]FIG. 1 is a schematic representation of an oscillating sander shown at an angle from above,  
         [0016]    [0016]FIG. 2 is a view of a retaining element shown at an angle from the front,  
         [0017]    [0017]FIG. 3 is a view of the retaining element in FIG. 2 shown at an angle from the back,  
         [0018]    [0018]FIG. 4 is a sectional drawing along the line IV-IV in FIG. 3,  
         [0019]    [0019]FIG. 5 is a variant of FIG. 2 with a passage formed by two intersecting incisions,  
         [0020]    [0020]FIG. 6 is a variant of FIG. 2 with a protrusion extending against the transport direction,  
         [0021]    [0021]FIG. 7 is a sectional drawing along the line VII-VII in FIG. 6, and  
         [0022]    [0022]FIG. 8 is a variant of FIG. 2 with a separate support piece. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]    [0023]FIG. 1 shows a schematic representation of a hand-guided oscillating sander  10  with an electric motor (not shown in greater detail) in a first housing part  66 . Two handles  68 ,  70  are integrally molded on the housing part  66 , i.e., a first handle  68 —comprising an operating switch—extending in the longitudinal direction toward an operator, and a second handle  70  located on a side furthest away from a working surface in the upper region of the oscillating sander  10 . Furthermore, a third handle  74  is secured in the longitudinal direction to a side opposite from the first handle  68 .  
         [0024]    A second housing part  78  is located on the side closest to the working surface abutted by a plate-shaped tool carrier  76  driven by the electric motor. A fan (not shown in greater detail) of a dust and chip removal device is located in the housing part  78 . A substantially rectangular connection piece  94  forming a transport channel  12  is integrally molded on the housing part  78  (FIGS. 1 and 4). During operation, the fan picks up dust and chips from the working surface and blows them through the transport channel  12  into a storage container  16  fitted onto the transport channel  12 .  
         [0025]    A dust and chip removal device having a funnel-shaped retaining element  18  is located between the transport channel  12  and the storage container  16  to prevent the dust and chips from flowing back out of the storage container  16  (FIGS. 1, 2,  3  and  4 ). The retaining element  18  is designed as a dual-component, injection-molded part. The retaining element  18  comprises a support piece  64  and/or a frame made of hard-elastic plastic, i.e., polypropylene (PP), having a rectangular base surface on which side walls  80 ,  82  made of hard-elastic plastic tapering toward each other and extending in the direction of the storage container  16  and/or in the transport direction  44  of the sanding dust are integrally molded. In addition to polypropylene (PP) and a hard-elastic plastic, other materials appearing reasonable to one skilled in the art are also feasible.  
         [0026]    Moreover, walls  48 ,  50  made of an elastomer, i.e., an ethylene-propylene rubber (EPDM), are integrally molded on the support piece  64 , forming a top side and a bottom side. The side walls could also be designed integral with the walls forming the top side and the bottom side. The walls  48 ,  50  extend toward each other in the transport direction  44 , each one along an exponential function. Instead of ethylene-propylene rubber, rubber could be used as well. On their ends pointing toward the storage container  16 , the walls  48 ,  50  come to bear against each other and form a passage  28  closed by means of their inner holding forces. The walls  48 ,  50  have a thickness that decreases in accordance with an exponential function in the direction toward the passage  28 . The retaining element  18 , by means of its walls  48 ,  50 ,  80 ,  82 , forms a channel  36  tapering in the direction of the passage  28 .  
         [0027]    If the oscillating sander  10  is operated, dust and chips are blown into the channel  63 . When a certain delivery pressure is reached, the walls  48 ,  50  are displaced against their inner holding force, and the passage  28  is opened. The sanding dust is accelerated through the tapering channel  36  and transported into a rear region of the storage container  16  furthest away from the passage  28 . The storage container advantageously fills in the direction of the passage  28  starting at an end furthest away from the passage  28 . If the oscillating sander  10  is switched off, the passage  28  is re-closed automatically by means of the inner holding forces of the walls  48 ,  50 . Instead of two soft-elastic walls  48 ,  50 , only one wall could be made soft-elastic.  
         [0028]    An alternative, funnel-shaped retaining element  20  is shown in FIG. 5. Components that essentially remain the same are basically labelled with the same reference numerals in the exemplary embodiments shown. Moreover, the description of the exemplary embodiment in FIGS. 1 through 4 can be referred to with regard for features and functions that are the same.  
         [0029]    The retaining element  20  comprises a basic framework made of hard-elastic plastic, i.e., polypropylene (PP), having two side walls  84 ,  86 —one wall  52  forming a top side, and one wall  54  forming a bottom side. The walls  52 ,  54  extend toward each other in the transport direction  44 , each one along an exponential function. The retaining element  20  forms a channel  38  that tapers in the transport direction  44 .  
         [0030]    On an end pointing toward the storage container  16 , the basic framework is closed by means of a wall  88  made of an elastomer, i.e., ethylene-propylene rubber (EPDM), in which said wall two diagonally extending, intersecting incisions  56 ,  58  are applied, forming a passage  30 . Instead of a basic framework made of hard-elastic plastic, it would also be feasible to produce many or all of the walls out of a soft-elastic plastic.  
         [0031]    [0031]FIGS. 6 and 7 show a retaining element  22  made of an elastomer or ethylene-propylene rubber (EPDM) having an oval base surface for an oval connecting piece  96 —forming a transport channel  14 —of an oscillating sander. The retaining element  22  forms a channel  40  that tapers in the transport direction  44 , whereby the tapering is produced by an initially rectangular protrusion  46  extending against the transport direction  44 . The protrusion  46  is located in the center region of the retaining element  22 , comprises an oval base surface, and is designed to taper in the nature of a funnel and/or it forms a cone tapering against the transport direction  44 . Incisions  90  extending in the circumferential direction are formed in the retaining element  22  in a region of the retaining element  22  abutting the protrusion  46  radially outwardly next to a storage container, which said incisions form a passage  32 . Furthermore, incisions  92  extending in the radial direction would also be feasible, as indicated in FIG. 6. The incisions  90 ,  92  are closed by means of an internal holding force of the retaining element  22  when the oscillating sander is switched off, and they open when a certain amount of delivery pressure is applied.  
         [0032]    A ring seal  60  is integrally molded on the retaining element  22  that seals radially outwardly at a connecting piece  26 —fitted onto the transport channel  14 —of a storage container (not shown in greater detail) and, in the direction of the oscillating sander, at an end face of the connecting piece  96  facing the storage container.  
         [0033]    [0033]FIG. 8 shows a view of a retaining element  24  made of an elastomer or ethylene-propylene rubber (EPDM) having walls  98 ,  100  extending toward each other in the transport direction  44  that come to bear against each other at an end pointing in the transport direction  44 , forming a passage  34 . The retaining element  24 —like the retaining element  22 —has an oval base surface and forms a channel  42  tapering in the transport direction  44 . The walls  98 ,  100  have a thickness that decreases in accordance with a linear function in the direction toward the passage  34 . A hook-shaped seal  62  is integrally molded on the retaining element  24 , which said hook-shaped seal seals radially outwardly at a connection piece  26  of a storage container (not shown in greater detail) and against the transport direction  44  at an end face of a connection piece  96  of an oscillating sander forming a transport channel  14 . In order to stabilize a region of the retaining element  24  closest to the connection piece  96  and/or the oscillating sander, a separate support piece  102  is provided that reaches radially from the outside into an annular groove  104  of the retaining element  24 .  
                                         Reference Numerals                                10   Hand power tool       12   Transport channel       14   Transport channel       16   Storage container       18   Retaining element       20   Retaining element       22   Retaining element       24   Retaining element       26   Connection piece       28   Passage       30   Passage       32   Passage       34   Passage       36   Channel       38   Channel       40   Channel       42   Channel       44   Transport direction       46   Protrusion       48   Wall       50   Wall       52   Wall       54   Wall       56   Incision       58   Incision       60   Seal       62   Seal       64   Support part       66   Housing part       68   Handle       70   Handle       72   Operating switch       74   Handle       76   Tool carrier       78   Housing part       80   Side wall       82   Side wall       84   Side wall       86   Side wall       88   Wall       90   Incision       92   Incision       94   Connection piece       96   Connection piece       98   Wall       100   Wall       102   Support piece       104   Annular groove