Abstract:
A portable power tool, in particular an angle grinder ( 10 ), includes a longitudinal housing ( 12 ) for accommodating a motor for driving a driven shaft ( 16 ) that is outwardly bent relative to the housing ( 12 ), the driven shaft being rotatably supported in a gearbox casing ( 14 ) and extending out of it with a free end that is provided to accommodate a sanding body. A protective cover ( 43 ) encompassing the sanding body is capable of being fastened on the gearbox casing ( 14 ) such that its rotation can be adjusted, and the rotational position of which is lockable using a notch lever ( 30 ). The device is made safer to operate and more cost effective to manufacture by the fact that the notch lever ( 30 ) is positioned transversely to the longitudinal axis of the angle grinder ( 10 ) and is pivotable around an axis ( 34 ) positioned substantially parallel to the housing ( 12 ).

Description:
BACKGROUND OF THE INVENTION 
   The present invention is based on a portable power tool. 
   A portable power tool is already known from DE 199 14 855 A1, which is designed as an angle grinder and is provided with a protective cover, the rotational position of which is fixable in the circumferential direction using a simple, releasable locking mechanism. Its catch mechanism is composed essentially of a flat spring, the projections of which are capable of being disengaged from recesses in the protective cover to allow the protective cover to be adjusted by hand, and the retention forces of which are impaired by deformation of the catch mechanism caused by intensive worksite use. 
   SUMMARY OF THE INVENTION 
   The present invention has the advantage that a protective cover with an associated robust, simple method for locking the protective cover in place is capable of being installed on conventional portable power tools, on angle grinders in particular, without making any structural changes, the locking method enabling the protective cover to be reliably fixed in any rotational position. 
   Due to the fact that the notch lever is positioned transversely to the longitudinal axis of the angle grinder and is pivotable around an axis situated substantially parallel to the housing, the tracks of motion of the notch lever are fixed; as a result, changes in the locking characteristics of the protective cover are prevented. 
   Due to the fact that the notch lever touches the protective cover in a detent position, the protective cover is fixable in this position in a form-locked or non-positive manner. 
   Due to the fact that the notch lever is elastically preloaded in the direction toward the protective cover, constant contact between the notch lever and the protective cover is ensured. 
   Due to the fact that the notch lever includes a pusher button on one free end and/or at least one centrally positioned engagement cam on the other end—the engagement cam engaging in the protective cover and holding it in place in a form-locked manner—an easy-to-operate, robust and exact detent means is created. 
   Due to the fact that the notch lever is pivotably supported on the housing, in particular on the gearbox casing, a flange screw must be loosened and screwed back into place to operate and install the notch lever. 
   Due to the fact that the pusher button of the notch lever extends transversely to the gearbox casing and past its circumference, it is easily accessible by at least one finger, in particular by the index finger of the operator&#39;s hand encompassing the housing in the working position, the protective cover can be adjusted conveniently and quickly, and operating error is prevented. 
   Due to the fact that the protective cover is capable of being engaged with the rigid engagement cam in a form-locked manner, the protective cover can be positioned in any rotational position largely without play such that it is secured against coming loose unintentionally. 
   Due to the fact that the gearbox casing has a flange that is capable of being screwed to the housing, whereby one of the flange screws also functions as rotational axis of the notch lever, the locking means of the angle grinder protective cover is easy to install on conventional angle grinders. 
   Due to the fact that the protective cover has engagement openings arranged in a semicircle for engagement by the engagement cams of the notch lever, the protective cover can be locked securely and in a form-locked manner in predetermined rotational positions relative to the portable power tool. 
   Due to the fact that the protective cover has a multiple-component design, whereby the first part is an annular collar, in particular having an outwardly-bent edge region, made of a strong material, and a second part is a disk-shaped main body, it is possible to manufacture the protective cover out of different materials in a particularly cost-effective manner, because the parts can be processed more favorably separately from each other, and the protective cover is capable of being manufactured as a lightweight component. 
   Due to the fact that the annular collar part includes an outwardly-bent region designed in the manner of a hat brim, which includes the engagement openings, the second part, i.e., the main body of the protective cover, can be made of particularly thin material, because the collar part alone absorbs the retention forces between the engagement openings and the engagement cams on the notch lever. 
   Due to the fact that an annular flat spring is provided in the fastening region of the angle grinder protective cover on the neck of the gearbox casing, the annular flat spring retaining the protective cover on the gearbox casing axially, without play, in a radially rotatable manner, the fastening region of the gearbox casing that supports the protective cover can be composed of relatively roughly tolerated plastic, because the annular flat spring compensates for dimensional deviations and/or wear in the fastening region. 
   Due to the fact that the gearbox casing includes a fastening region for the protective cover configured as a cylindrical plastic neck, the fastening region belonging to a bearing flange that concentrically encompasses the driven shaft, the weight of the gearbox casing can be reduced and, therefore, so can the weight of the entire portable power tool, so the portable power tool is easier to handle and can be operated without tiring the operator. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention is described in greater detail below with reference to an exemplary embodiment with associated drawing. 
       FIG. 1  shows the portable power tool with protective cover in an exploded view, 
       FIG. 2  shows the portable power tool according to  FIG. 1  with assembled protective cover before installation, 
       FIG. 3  shows the individual parts of a dual-component exemplary embodiment of the protective cover, 
       FIG. 4  shows the protective cover according to  FIG. 3 , assembled, 
       FIG. 5  shows a second exemplary embodiment of a dual-component protective cover, in an exploded view, 
       FIG. 6  shows the exemplary embodiment according to  FIG. 5 , assembled, 
       FIG. 7  shows a dual-component protective cover with plastic collar and metallic main body, and 
       FIG. 8  shows a single-component protective cover according to the present invention, composed of metal. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  shows the front region of a portable power tool  10  designed as an angle grinder, longitudinal housing  12  of which determines a longitudinal axis  13  of portable power tool  10 . A gearbox casing  14  is flange-mounted to housing  12 , out of which a driven shaft  16  exits at a right angle to longitudinal axis  13 . A sanding disk (not shown) is capable of being fastened to its free end, the sanding disk being encompassed by a protective cover  43  to protect the operator of portable power tool  10  from flying chips and/or parts of the sanding disk. 
   Gearbox casing  14  is fastened to housing  12  with flange screws  18  that engage in flange holes  20  extending parallel with longitudinal axis  13 . Gearbox casing  14  includes a bearing flange  22  that encompasses driven shaft  16  in an annular manner. Bearing flange  22  is configured in the shape of a plate in the region facing gearbox casing  14  and is connectable with gearbox casing  14  via a flange screwed connection  23  positioned substantially parallel to driven shaft  16 . 
   Bearing flange  22  includes a cylindrical neck  24  projecting upwardly outward at a right angle to longitudinal axis  13  and accommodating protective cover  43  on its outer circumference and including an annular groove  26  in an axial position nearly in the center, whereby its outer, ridge-like annular groove delineation  27  is interrupted at regular intervals by axial grooves  28  that are assigned to corresponding radial cams  46  in collar  44  of protective cover  43  and which are to be coupled, matching up with each other, using an insertion-rotation motion, in the manner of a key in a lock or a quarter-turn fastener system. 
   Protective cover  43  is composed of a disk-like, half-moon-shaped main body  53  with a central hole  55 , the outer edge  54  of which is outwardly bent and, as a result, extends in the manner of a partial cylindrical Jacket. Main body  50  encompasses, nearly halfway, the circumference of a circular-disk-shaped sanding body (not shown) that is driven in a rotary manner by driven shaft  16 , as is commonplace with angular grinders. Main body  50  is connected with a circular-ring-shaped collar  44  that includes a region  45  bent outwardly laterally in the manner of a hat brim. It extends in parallel with perforated disk  52  of main body  50  and concentrically to central hole  55  of perforated disk  52 . 
   Collar  44  is connectable with main body  50  by adhesion, welding, soldering or the like. It Includes impressed, radially inwardly extending radial cams  46 . Their dimensions match those of axial grooves  28  in neck  24  of bearing flange  22  such that they pass through them when inserted axially, then enter annular groove  26  when rotated radially, where they hold protective cover  43  tightly in an axially secured manner. In its region that is bent outwardly in the manner of a hat brim, collar  44  includes engagement openings  48  into which engagement cams  32  of a notch lever  30  fit and enter and thereby secure protective cover  43  against twisting on gearbox casing  14 . 
   The particular different widths and identical height of radial cams  46  are matched in terms of dimensions with the corresponding annular grooves  26  having uniform width, and axial grooves  28  having different widths, on neck  24 . Only protective covers  43  that fit particular neck  24  grooved in a coded manner can be guided axially via the collar over neck  24  and fastened thereto in an operationally correct manner. To this end, the manufacturer must first slide a snap-ring-like annular spring  40  slotted in a particular manner axially over neck  24 , whereby its spring cam  42  must be guided through one of the axial grooves  28  and then, perhaps after being twisted radially, staked in annular groove  26  or fixed in place by bending it upward or downward in a pocket  41  on lower edge of neck  24 , thereby securing it against coming loose. 
   The operator then guides protective cover  43  with radial cams  46  over axial grooves  28  of neck  24  until radial cams  46  contact the lower edge of annular groove  26 , and protective cover  43  can then only be twisted, whereby radial cams  46  enter annular groove  26  laterally in the manner of a quarter-turn fastener and are held securely therein and prevented from coming out axially, whereby they are retained in an axially preloaded and, therefore, play-free manner by annular spring  40 . 
   On its side furthest from the housing, notch lever  30  includes, on the top, a region with engagement cams  32  designed to engage in engagement openings  48 . Notch lever  30  also includes, on its free end, a hole extending toward engagement cams  32  offset by nearly  90 , through which a flange screw  18  is guidable for screwing into a certain flange hole  20 , and which functions as pivot axis  34  of the notch lever. Notch lever  30  includes, nearly in the center, a transversely projecting, captively securable compression spring  36  with which notch lever  30  bears against gearbox casing  14  in a preloaded manner such that it can always bear against the outward bend  45  of collar  44  with a minimum force with its cams  32 , Thereby securing the engagement cams  32  in engagement openings  48 . 
   Main body  50  of protective cover  43  includes welding holes  53 , through which main body  50  can be welded and/or soldered with collar  44  and/or with outward bend  45 . 
     FIG. 2  shows—as does FIG.  1 —the spacial view of portable power tool  10  with protective cover  43 , whereby protective cover  43  is assembled and attached to welding holes  53  by welding and forms a unit with collar  44 . 
   Only gearbox casing  14  of portable power tool  10  is shown in  FIG. 2 , whereby the individual parts shown separately in an exploded view in  FIG. 1  are located in the final assembled position, clearly illustrating the arrangement of notch lever  30 . Going beyond  FIG. 1 ,  FIG. 2  shows an axial arrow  58 , according to which protective cover  43  is slid over neck  24  and then twisted in accordance with a curved arrow  60  such that the round edge of main body  50  is turned relative to the position shown. As a result, operating personnel situated behind the tool engagement site in the extension of longitudinal axis  13  are protected against dust, chips, splinters or the like. 
   To turn protective cover  43  out of its selected detent position, an end region of notch lever  30  configured as a pusher button  38  must be swiveled away from protective cover  43  and toward gearbox casing  14 , so that the two engagement cams  32  come out of the two diametrically opposed engagement openings  48  and no longer prevent protective cover  43  from turning. Notch lever  30  is released only when in the desired rotational position, so it can engage with its engagement cams  32  in engagement openings  48 —preloaded by compression spring  36 —and secure protective cover  43  against unintentional motion. 
     FIG. 3  shows a further exemplary embodiment of a protective cover  430  that differs from protective cover  43  in  FIGS. 1 and 2  in that collar  440  is composed of plastic or metal that can engage via a radially outwardly extending snap-in hook  64  in corresponding snap-in openings  65  of main body  500  by inserting it through central hole  51  and fixing it in place via overlatching, so that its, hat-brim-like region  66  comes to rest on main body  500 . 
   In this case, engagement openings  48  are located in main body  500 , which must be designed thicker in this case to be able to absorb the engagement forces and/or retention forces for securing protective cover  24  on gearbox casing  14  by notch lever  30 . 
     FIG. 4  shows protective cover  430  in the installed state, whereby it is clear that snap-in hooks  64  project radially outwardly and grip over main body  500  and secure its position relative to collar  440 .  FIG. 5  shows a further exemplary embodiment of a removed protective cover  432 , collar  441  of which is welded with main body  501 , thereby corresponding substantially to protective cover  43  according to  FIG. 2 . 
     FIG. 6  shows protective cover  432 , whereby, unlike the previous figures, it shows that welding holes  53  are welded with collar  44 . 
     FIG. 7  shows a protective cover  434 , the collar ring  48  of which is composed of plastic which is applied by injection molding to main body  504  in the region of its central hole  51 . 
     FIG. 8  shows a single-component protective cover  433  made of steel, in the case of which, as also shown in  FIG. 7 , engagement openings  48  are located in main body  502  ( 504 ), whereby the advantage of this protective cover is that it is capable of being manufactured in a single working step, even though more material is required in this case than with the other versions.