Patent Abstract:
A manual power grinder has a housing, a motor received in the housing, a grinding disc driven by the motor and located on an underside of the motor; a drive shaft arranged so that said drive shaft and the motor are located parallel to one another and vertically to the grinding disc in said housing and are in rotational communication with one another, and a gear unit providing the rotational communication of the motor and the drive shaft and located below in the housing.

Full Description:
CROSS-REFERENCE TO A RELATED APPLICATION 
   A patent application Ser. No. 11/234,779 has been filed, which contains a similar subject matter. 
   BACKGROUND OF THE INVENTION 
   The present invention relates to a manual power grinder, in particular a battery-powered manual power grinder. 
   Battery-powered manual power grinders with usually a plurality of relatively heavy NiCd cells as energy storing means already exist, having the same mechanical components as the manual power grinders corresponding to them that have a mains voltage connection, such as the same gear wheels, fan wheels, and compensation mass for eliminating imbalances, as well as eccentric drives. 
   A disadvantage of the known hand power tools is their large-volume structural size and their great weight, because they have large, heavy components. This worsens the ergonomics, handiness, and production costs of the known battery-powered manual power grinders. 
   SUMMARY OF THE INVENTION 
   Accordingly, it is an object of the present invention to provide a manual power grinder, which avoids the disadvantages of the prior art. 
   In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a manual power grinder; comprising a housing; a motor received in said housing; a grinding disc driven by said motor and located on an underside of said motor; a drive shaft arranged so that said drive shaft and said motor are located parallel to one another and vertically to said grinding disc in said housing and are in rotational communication with one another; and gear means providing the rotational communication of said motor and said drive shaft, said gear means being located below in said housing. 
   When the manual power grinder, in particular a battery-powered manual power grinder is designed in accordance with the present invention it has the advantage that an especially lightweight, handy, compact battery-powered manual power grinder of the shape and size of a travel iron has been created with an especially high surface power per battery charge. 
   Because of the parallel arrangement of the motor with the motor pinion and the drive shaft with a drive pinion side by side, vertically to the plane of the grinding plate, with the flat sides of the two pinions extending close to and parallel to the grinding plate, the distribution of mass is shifted even closer to the grinding plate, and there is an especially low center of gravity of the hand power tool. Moreover, because of the parallel arrangement of the motor and the drive shaft side by side vertically in the housing, inexpensive, straight-toothed spur gears can be used for force transmission or as a speed-reducing gear with a ratio of approximately i=3 between the motor and the eccentric drive, instead of previous versions that use a toothed belt gear or—in the case of an angled arrangement of the motor relative to the grinding plate—an angle gear. 
   Because the motor pinion has air guide vanes on one flat side, two functions are united in this compact machine element in a space-saving way. As a result, the motor and the motor pinion can be made especially short, or in other words with a reduced axial length, and the center of mass can be especially low and the housing can be designed as especially low in height. Moreover, compared to the previous construction with a separate engine fan, this kind of separate component can be omitted, and the costs for material and assembly of the battery-powered manual power grinder of the invention are made even more favorable. 
   Because the gear wheel, on its side toward the motor, is designed as a radial fan with curved air guide vanes, the motor and at the same time the motor pinion, or the drive pinion meshing with it, can be cooled with high efficiency. 
   Because the drive pinion is designed to fit the motor pinion and as a straight-toothed spur gear meshing with the motor pinion and is located in the lowermost region of the housing, the center of mass of the battery-powered grinder is located lower than was ever attained before. 
   Because the drive pinion has recesses and accumulations of material on its flat sides, it simultaneously forms an especially compact compensation mass which can moreover be located so that it protrudes axially past the grinding disk bearing toward the grinding disk and hence very close to the grinding disk—and thus is axially short—so that only small imbalancing tilting moments can occur between the grinding disk and the drive shaft, and the compensation mass can be kept small. 
   Because the drive pinion also has an eccentric peg, in particular integrally with it, it simultaneously forms the most important part of the eccentric drive. 
   Because the iron-shaped or triangular grinding disk has a grinding plate with a step pointing toward the workpiece in the rear, the height of which step is equivalent to that of a standard Velcro closure, in its tip region it can receive a separate triangular grinding disk that on its underside is flush with the rearward-adjoining remainder of the surface and has a padding layer, which extends flatly and with the same thickness and height toward the padding layer of the region of the grinding disk adjoining it to the rear. 
   Because at the front, a narrow, elongated grinding tongue can be clipped detachably to the tip of the iron-shaped grinding disk, even the tiniest, narrow workpiece regions can be machined with the battery-powered grinder, so that the range of use of the battery-powered grinder is enlarged. 
   Because the switch trigger of the battery-powered grinder is a leaf-springlike lever that can be suspended and in particular clamped by its lower end between the housing shells, an especially sturdy, lightweight, inexpensive design of the lever is created. 
   Since the lithium ion battery has almost no self-discharge, the battery-powered grinder is fully ready for use without restriction even after long intervals between uses; in these intervals, it can rest for an arbitrarily long time on a charging shell in the charging mode, without the battery being impaired thereby. The charging shell can be placed, standing securely, on a level shelf and need not be secured or even grasped firmly when the battery-powered grinder is removed. Because the battery-powered grinder can automatically be put by its charging plug, located on the rear end of the housing, upon placement on the charging shell, into electrical contact with counterpart contacts of the charging shell, and there is no need to pay attention to additional cords or coupling plugs, the power grinder is always ready for fast removal using only one hand; no plug has to be pulled out, and no mounting has to be removed. Moreover, it is automatically assured at all times that the battery-powered grinder is charged. 
   The compact lithium ion battery, particularly designed as a pair of batteries, sits without play, positionally secured, tensed in the upper region of the grip and is integrated into the strength structure of the grip, and the battery increases the dimensional stability of the grip while using little material for the half shells of the housing. 
   The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims the invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side view of the partly open battery-powered grinder; 
       FIG. 2  is a front view of the battery-powered grinder; 
       FIG. 3  is a view of the battery-powered grinder from below; 
       FIG. 4  is a detail showing the motor with the motor pinion from the side; 
       FIG. 5  is a detail showing the eccentric drive with the grinding plate from the side; 
       FIG. 6  is a view of the eccentric drive wheel from below; 
       FIG. 7  is a top view on the gear wheel of  FIG. 6 ; 
       FIG. 8  is a sectional view of the gear wheel of  FIGS. 6 and 7 ; 
       FIG. 9  is a detail showing a top view of the motor pinion; 
       FIG. 10  shows the motor pinion from below; 
       FIG. 11  is a sectional view of the motor pinion; 
       FIG. 12  is a three-dimensional top view on the grinding disk; 
       FIG. 13  is a plumb top view on the grinding disk; 
       FIG. 14  is a longitudinal section through the grinding disk; 
       FIG. 15  is a view of the grinding disk from below; 
       FIG. 16  is a three-dimensional view of a grinding tongue; 
       FIG. 17  is a top view on the grinding tongue; 
       FIG. 18  is a longitudinal section through the grinding tongue; 
       FIG. 19  is a three-dimensional view of the switch trigger; 
       FIG. 20  is a view of the switch trigger from behind; 
       FIG. 21  is a front view of the switch trigger; 
       FIG. 22  is a cross section through the switch trigger; and 
       FIG. 23  is a view of the housing from below. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  shows an especially small, compact battery-powered grinder  10 , whose housing  12  is shown opened, by removal of the right-hand housing shell  16 , making it possible to look into the interior of the housing  12 , and the parts located in the housing shell  14  and described in further detail below. 
   The housing  12  is formed of two half-shells  14 ,  16 , which can be put together, braced tightly against one another, in a center plane  15 . To that end, five screws extend through bores in the upper half-shell  16  ( FIG. 2 ) in five screw domes  40 ,  41 ,  42 ,  43 ,  44  of the lower half-shell  14  in order to firmly hold the two against one another. The upper region of the housing  12  forms a curved grip region that can be grasped easily even by small hands. 
   Beneath it, in the viewing direction, the housing  12  has a triangular grinding disk  18 , shaped like an iron for ironing clothes, whose tip  19  points to the right in the viewing direction and defines the recommended feed direction. The grinding disk  18  has a padding layer  25  and is secured in captive form to the housing  12 , in particular suspended in it, via two pairs  20 ,  22  of vibrating bodies, which form four elastic columns screwed to the outer corners of the grinding disk. 
   A vertically located motor  24  that can be powered by direct current is seated between the grinding disk  18  and the grip region of the housing  12 . It can be powered by means of a lithium ion battery  26 , or in particular a pair of such batteries placed side by side, and is electrically connected to the battery or batteries via electric cords  28  extending in the interior of the housing  12 . Two of the electric cords  28  connect the battery  26 , via an electronics unit  32 , to a charging plug  30  located at the rear, in the upper region of the housing  12 , so that on being connected in plug-in fashion to the mating plug of a charging device that is ready for operation, the battery  26  can easily be charged. The electronics unit  32 , with elements for converting alternating current to direct current and for regulating the battery charging operation, is seated on a printed circuit board  33 , fixed toward the top in the grip region  17  of the housing  12 . 
   On the right in the viewing direction, there is a switch trigger  34  toward the face end on or in the housing  12 ; its pushbutton  340  protrudes out of an opening  35  in the housing  12 , with flush contours to the outside, where it can easily be reached by the user&#39;s hand. Via a key cam  344 , the switch trigger  34  can be braced against a switch key  361  of an electric switch  36  for actuation, so that when the pushbutton  340  is pressed inward, the switch  36  can be put in the activation position, and when the pushbutton  340  is let go it can be put in the deactivation position. 
   The spring-tonguelike switch trigger  34  can be fixed with its lower region, by means of a positioning rib  38 , in suitable central recesses in the housing shells  14 ,  16 , so that it is fastened on the order of a toggle switch on the housing  12  and acts resiliently on the switch  36 . 
   A motor shaft  46  emerges from the motor  24  at the bottom, and on it a motor pinion  48  is firmly held in a manner secure against rotation by its central bore  49 . On the flat top  47  of the motor pinion  48 , ventilator ribs  52  in the form of curved air vanes are distributed at regular intervals, in particular being molded, for instance pressed or cast, so that the motor pinion  48  acts not only as a gear element but also as a ventilator, particularly for cooling the motor. The motor pinion  48  has straight teeth  50 , with which it meshes with counterpart teeth  56  of a drive pinion  54 . The flat underside  51  of the motor pinion  48  is located directly close to the lower horizontal housing wall  13  and indirectly but still closely, spaced apart from it by less 5 mm, to the top  78  of the grinding disk  18 . 
   Regular recesses  53  for reducing the weight are located on the underside  51  of the motor pinion  48  and are spanned by spokelike webs  55 , thus lending the motor pinion  48  quite adequate strength. The drive pinion  54  has a larger diameter than the motor pinion  48 , so that a ratio of i=2 to 3 is created. The teeth  56  of the drive pinion  54  fit between those of the motor pinion  48 . By means of a drive shaft  58 , the drive pinion  54  is supported in the housing  12  next to and parallel to the motor  24  via one upper and one lower drive bearing  62 ,  64 . On its underside, the drive pinion  54  has an eccentric element  70  ( FIGS. 5 ,  6 ,  8 ), whose eccentric engagement  60  with the grinding disk  18  is effected via a disk bearing  68 , so that the rotating drive pinion  54  lends an orbital motion to the grinding disk  18  by means of the eccentric element  70 . 
   To the rear, the housing  12  has a central suction extraction opening  66 , through which grinding dust can be vacuumed out by means of the connection of a vacuum cleaner hose, not shown, which is formed on the underside  80  of the grinding disk  18  or of the grinding sheet  77 . 
     FIG. 2  shows a front view of the battery-powered vibrating grinder  10 , looking toward the center plane  15  of the motor housing  12 , its half-shells  14 ,  16 , the switch trigger  34 , a transparent window  45 , and the tip  19  of the grinding disk. The grip region  17  is narrower in width than the grinding disk  18 . At the top front, the motor housing  12  has the transparent window  45 , which is put in place and extends along the parting plane  15  and allows one to look through openings in the half-shells  14 ,  16  to see colored light-emitting diodes, not shown in detail, that serve particularly to indicate the charge status. 
     FIG. 3  shows a view from below on the battery-powered vibrating grinder  10  and the underside  80  of the grinding disk  18 , or a grinding sheet  77  ( FIG. 5 ) fixed to it by means of a Velcro closure or the like, the outline of the grinding sheet being shown in dashed lines. The iron-shaped contour of the grinding disk  18  and of the grinding sheet  77  can be seen. The grinding disk  18  is composed of a front, removable, equilateral triangular grinding disk  180  and a fixedly disposed remaining grinding sheet  181 , which forms a regular trapezoidal differential face that together with the small triangular grinding disk  180  forms the iron shape. 
   The grinding disk  18  has a hooked layer which corresponds to a velour layer of commercially available grinding sheets and is pierced by round inlet openings  777  for removing grinding dust as well as by four screw holes, not identified by reference numeral, for fastening the vibrating bodies  20 ,  22 . 
   A corresponding grinding sheet  77  can be put together from a front grinding sheet  770  in the shape of an equilateral triangle and a remaining grinding sheet  771  behind it, optionally offset from one another by a perforated intentional tearing line, and has eleven of the inlet openings  777  for the passage through them of grinding dust that is vacuumed away. The front grinding sheet  770  is equivalent to a standard triangular grinding sheet with curved outer edges for commercially available triangular grinders. The remaining grinding sheet  771  forms a special shape, with two parallel, straight outer edges, one curved front edge, flushly adjoining the curved outer edge of the grinding sheet  770 , and one outward-curved rear edge. The remaining grinding sheet  771  enlarges the effective grinding area, so that the removal power of the battery-powered grinder is markedly improved over known triangular grinders with a standard triangular grinding sheet  770 . 
     FIG. 4  shows a side view of the motor  24  in the form of a detail, with the motor shaft  46  and the motor pinion  48  seated on it, with the teeth  50  and the ventilator ribs  52  on its flat top  47 . It can be seen that a bush, not identified by reference numeral, is seated in the bore  49  for the sake of engaging the motor shaft  46  in such a way that it is secure against rotation. 
     FIG. 5  shows a detail of a compact structural group, made up of the grinding disk  18  with the meshing drive pinion  54  and the power takeoff shaft  58 . The drive pinion  54 , with its eccentric peg  70 , engages a disk bearing  68 , embodied as a roller bearing. As a result, the rotation of the eccentric peg  70  is transmitted not directly but rather indirectly to the grinding disk  18 , imparting an orbital motion to the grinding disk. The disk bearing  68  is seated in a recess, acting as a bearing seat  82 , on the top  78  of the grinding disk  18 . A grinding sheet  77  is seated on the underside  80  of the grinding disk  18 , held there by a Velcro closure. The drive shaft  58 , with its lower end, reaches in a manner secured rotation into a central blind bore  72  on the top of the drive pinion  54 . It is guided in one upper and one lower drive bearing  62 ,  64 . 
     FIG. 6  shows the underside  57  of the drive pinion  54 . Straight teeth  56  are located on the circular circumference of the drive pinion, and the upward-pointing eccentric peg  70  and the compensation mass  74  designed as an annular segment can both be seen. 
     FIG. 7  shows the top  59  of the drive pinion  54  with the central blind bore  72  and the eccentric recesses  76 , which—like the compensation mass—also serve to compensate for imbalance. 
     FIG. 8  shows a longitudinal section through the drive pinion  54 , clearly showing its design and its integral nature with the eccentric peg  70 , the central blind bore  72 , the compensation mass, and the recesses  76 . 
     FIG. 9  shows the top  47  of the motor pinion  48  as a detail. Its central bore  49  for the passage through it of the motor shaft  46  can be clearly seen along with the straight teeth  50  and the ventilator ribs  52 . 
   The underside  51  of the motor pinion shown in  FIG. 10 , in addition to the characteristics shown in  FIG. 9 , shows the recesses  53  that serve to reduce weight and the spokelike webs  55  fitting over these recesses. 
     FIG. 11  shows a longitudinal section through the motor pinion  48 , in which the details mentioned in conjunction with  FIGS. 9 and 10  are seen especially clearly. 
     FIG. 12  is a three-dimensional view of the grinding plate  188  of the grinding disk  18 , looking toward the top  78  thereof. Its triangular shape—like the soleplate of an iron—is clearly shown, as is the fact that—as in an iron—the tip  19  points forward. The seats  84 ,  86  for retaining the vibrating bodies  20 ,  22  can be seen clearly; these bodies can be secured to the seats, in particular with a screw or the like that can be screwed in from below. Besides netlike annular and radial ribs  89 , or ribs  89  that are parallel to the outer contour, wider radial ribs  85  can be seen, which form the top of dust passage conduits  94  ( FIG. 15 ) that are open at the bottom and whose axial outlet openings  87  are seated on the top  78  of the grinding disk  18  in the outer annular ribs  89 . From these, grinding dust that occurs can be removed to the outside through a half-moonshaped inlet opening  661  ( FIG. 23 ) in the lower housing wall  13  of the housing  12 , through a conduit ( FIGS. 1 and 23 ), formed by curved housing walls  660 , to the suction extraction opening  66 . The dust entry takes place on the underside  80  of the grinding disk  18  through eleven inlet openings  777 . 
     FIG. 13 , with a plumb top view on the grinding plate  188 , shows the details for explaining  FIG. 12 ; the ribs  85  of the suction extraction conduits  83  are more clearly visible than in  FIG. 12 , as are their axial outlet openings  87  on the inside of the outermost annular rib  89 . Suction extraction air flows through them via the through opening  661  in the lower housing wall  13  to the suction extraction opening  66  at the rear end of the battery-powered grinder  10 . 
     FIG. 14  shows a longitudinal section through a grinding plate  188 , whose underside  80  in the front region  81  forms a step  88  toward the top. This step  88  is the same height as the Velcro closure system that for instance comprises one layer of hooks and one layer with loops, by which the triangular grinding disk  180  is detachably secured to the grinding plate  188 . As a result, the padding layer  25  of the grinding disks  180 ,  181  can have a uniform thickness and can extend in a straight line, or level, at the same height over the entire grinding disk  18 . The front and rear regions  81 ,  91  of the grinding plate  188  are offset from one another by a stepped edge  90 . 
     FIG. 15  shows the underside  80  of the grinding plate  188  with the dust passage conduits  94 , which form ribs  85  on the top of the grinding plate  188  and end in the suction extraction openings  87 . There is also a detent opening  92  for suspending an additional grinding disk, shown as a grinding tongue  1800  ( FIG. 16 ). 
     FIG. 16  shows the grinding tongue  1800  in a three-dimensional view; its grinding tip  1820 , which is both elongated and protrudes toward the front and the coupling face  1840  can be seen clearly; below the underside  1880 , a suitably narrow, elongated grinding sheet can be attached. 
     FIG. 17  shows the top view on the grinding tongue  1800 ; a resilient coupling tongue  1860  is located in the middle of the edge  1910 , toward the tool, of the coupling face  1840 , and when the grinding tongue  1800  is secured to the grinding plate  188 , this face, instead of the triangular grinding disk  180 , enters the detent opening  92  and firmly holds the grinding tongue  1800  there. Lateral top edges  1900  on the coupling face  1840  for positioning and retaining the grinding tongue  1800  on the grinding plate  188  assure a play-free, firm coupling connection. 
     FIG. 18  shows a longitudinal section through the grinding tongue  18  and shows that its underside  1880  is level and is intended for receiving suitable elongated, narrow grinding sheets. 
     FIG. 19  shows a three-dimensional detail of the leaf-springlike switch trigger  34 . Its shell-shaped pushbutton  340  is located in the upper region and is provided with a face end  341  curved toward the front. This assures easy manipulation. The resilient body of the switch trigger  34  adjoins it toward the bottom, and oblique reinforcing ribs  348  are located in the upper region between the pushbutton  340  and the spring body  343 . 
   The back side  342  of the pushbutton  340  is hollow, because of the shell-like design, and is oriented toward the interior of the housing. The spring body  343 , on its back side, has a key cam  344 , which serves to enable access to the switch key of the switch  36 . 
   In the lower region, the spring body has a transversely extending pinlike region, which serves as a positioning rib  38  and retains the switch trigger  34  without play, fastened in captive fashion, in suitable recesses in the housing shells  14 ,  16  of the housing  12 . 
     FIGS. 20 through 22  show the switch trigger from behind, from the front, and in longitudinal section, making the explanations of  FIG. 19  clearer. 
     FIG. 23  shows the underside of the battery-powered grinder  10  with the grinding disk removed; the half-moonshaped inlet opening  661  can be clearly seen centrally to the center plane  15 —and both half-shells  14 ,  16 —behind the eccentric peg  79  and the disk bearing  70 . The view is also opened up to the underside of the front and rear vibrating bodies  20 ,  22  that are arranged in pairs. 
   It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above. 
   While the invention has been illustrated and described as embodied in a manual power grinder, in particular a battery-powered manual power grinder, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. 
   Without further analysis, the foregoing will reveal fully revela the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of the invention.

Technology Classification (CPC): 1