Abstract:
A power tool includes a guard hood to be fixed on a tightening neck via a securing device thereof. The securing device has a securing part, which is to be tightened via an actuation element, and a detent component which is adjustable between a detent or locked position and a nondetent or unlocked position. The actuation element acts upon both the securing part and the detent component.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is based on German Patent Application 10 2008 002 468.6 filed Jun. 17, 2008. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates to a power tool, in particular a handheld power tool, such as a ring-angle sander, and to a guard hood for a power tool. 
         [0004]    2. Background of the Invention 
         [0005]    From German Patent Disclosure DE 102 59 520 A1, an electric handheld power tool with a disklike rotating tool is known over which a guard hood fits that is retained with the aid of a tightening ring on a tightening neck of the power tool. There is also a tool receptacle in the tightening ring for the rotating support of the tool. The tightening ring for fixing the guard hood to the tightening neck is tightened with the aid of a screw. 
         [0006]    On the outside of the tightening ring, a detent component is also supported in articulated fashion. By means of a detent element, the detent component protrudes through a recess in the wall of the tightening ring and engages a set of teeth on the outer jacket of the tightening neck. In this way, a form lock in the circumferential direction between the tightening ring and the tightening neck can be created, which prevents twisting of the tightening ring and guard hood on the tightening neck. This increases safety, particularly in the event of breakage of the tool. 
         [0007]    The detent element is disposed on a detent grip, which is supported in articulated fashion on the outside of the tightening ring and can be pivoted manually between the detent position, in which the detent element is in engagement with the set of teeth on the tightening neck, and a nondetent or unlocked position. 
       OBJECT AND SUMMARY OF THE INVENTION 
       [0008]    The object of the invention is, with high functional safety, to simplify a power tool, in particular a handheld power tool, having a guard hood retained on a tightening neck via a securing device, in its handling and structural makeup, as well as to create a guard hood suitable as original equipment for such a power tool but also suitable as a conversion part or retrofitting part of power tools. 
         [0009]    In the power tool of the invention, by means of the common actuation of the securing part and the detent component via an actuation element a common adjustment of the securing part and detent component is attained, and thus in one work step, not only is the securing part put in its securing position, but the detent component is also put in its detent position relative to the tightening neck. 
         [0010]    Hence the actuation element is given a dual function: First, the securing part is tightened, and second, the detent component is adjusted into the detent position. A separate actuation of the detent component can thus be omitted. It suffices, via the actuation element, to put the securing part into the tightening position, and at the same time, via the actuation element, the detent component is adjusted into the detent position. The result is considerably simpler handling, achieved by structurally simple means. With the tightening of the securing part, this part exerts a radial clamping force, by way of which the guard hood is firmly clamped on the tightening neck. By way of the detent component which is in engagement with the tightening neck, additional securing is achieved, and this additional securing is embodied in particular as a form lock which is operative in the circumferential direction and/or the axial direction; for that purpose, the tightening neck has a circumferentially extending set of teeth on its jacket face that are engaged by the detent element in the detent position. 
         [0011]    A circumferential groove can moreover be provided on the tightening neck and preferably extends over the entire circumference of the tightening neck. In combination with the set of teeth, this leads to an embodiment in which the toothlike indentations forming the set of teeth extend in the axial direction, originating at the circumferential groove. 
         [0012]    The circumferential groove has the function of securing the guard hood axially on the tightening neck in form-locking fashion. This is preferably effected via the detent element of the detent component, which thus besides the securing in the circumferential direction is also given the function of securing in the axial direction. When the guard hood is adjusted in the circumferential direction, the detent element can be moved inside the circumferential groove. However, in principle, it is also possible for a further component, such as a pin or a peg on the guard hood or the tightening ring, to engage the circumferential groove. 
         [0013]    In an alternative embodiment, the circumferential groove is embodied separately from the set of teeth; for instance, the circumferential groove is axially offset from the set of teeth on the jacket face of the tightening neck. In this embodiment, the securing in the axial direction is effected via a separate component, such as the aforementioned pin or peg. 
         [0014]    The guard hood of the invention is preferentially used in handheld power tools, in particular electrically operated handheld power tools, with a rotating, preferably disklike tool, such as a ring-angle sander, in which the guard hood that surrounds the rotatingly supported tool of the power tool, is to be fastened via the securing device on a tightening neck of the power tool. The securing device of the guard hood has a securing part, which is to be tightened via an actuation element, and also has a detent component, which is to be adjusted by the tightening neck between a detent position and a nondetent or unlocked position. 
         [0015]    In the guard hood of the invention and its securing device, it is provided that the actuation element acts upon both the securing part and the detent component, and with the fastening of the securing part via the actuation element, the detent component is to be put simultaneously into the detent position. Despite the dual function of the securing device, the result is a simple construction of the guard hood, which as a functional unit with its securing device also forms a spare part and retrofitting part that—at least without major requirement for adaptation—can also be used to replace guard hoods of different construction in many power tools. 
         [0016]    The securing par is preferably embodied as a tightening ring, which is laid around the tightening neck and tightened via the actuation element. In principle, however, structurally different securing with which the guard hood is to be secured to a component of the power tool can also be considered. 
         [0017]    In a preferred embodiment, the detent component is retained solely on the securing part, so that the securing part and the detent component form a common module which is to be adjusted by the actuation element. The actuation element too can be retained directly on the securing part, particularly when embodied as a screw that in the case of an embodiment as a tightening ring connects two radially upward-bent end portions of the tightening ring in a known manner. The free face end of the screw preferably acts as the contact face with which the screw is in contact with the detent component and adjusts the detent component from the nondetent position into the detent position. 
         [0018]    In principle, however, it is also possible to retain the detent component on some other tool component, for instance directly on the guard hood or on a housing part of the power tool. It is furthermore possible for the actuation element to be embodied not as a screw but instead as a toggle fastener, and the toggle fastener acts on the detent component during the tightening process. Optionally, the actuation element is retained not on the tightening ring but on some other component, such as the guard hood or a housing part. 
         [0019]    Various possibilities of movement for the detent component upon the transfer from the nondetent position to the detent position can be considered. Preferably, the detent component executes a pivoting or rotary motion then, but within the scope of the invention a translational adjusting motion or a mixed translational-rotary adjusting motion is possible. 
         [0020]    In the case of articulated support, the engagement or contact point is located between the actuation element and the detent component, spaced apart from the joint axis of the detent component, so that it is assured that a resultant torque becomes operative about the joint axis, and by means of this torque the detent component is adjusted into the detent position. 
         [0021]    It may furthermore be expedient to associate a spring element with the detent component, the spring element advantageously being braced on the same component as the detent component, in particular on the tightening ring, and subjecting the detent component to force in the direction of the nondetent position. It is thus assured that the detent component is automatically restored to the nondetent position by the action of the spring element as soon as the actuation element is adjusted into the release position, in which the tightening ring is also located in the relaxed state. Thus with a single adjusting motion of the actuation element, on the one hand the tightening ring is tightened and simultaneously the detent component is adjusted into the detent position, and on the other, upon an opposite motion of the actuation element, the tightening ring is relaxed and at the same time the detent component is adjusted into the detent position. 
         [0022]    However, it may also be expedient, in addition or alternatively to the spring element, to provide mechanical coupling between the actuation element and the detent component, by way of which coupling the detent component, upon a releasing motion of the actuation element, is pulled by the actuation element into the nondetent position. The coupling can be effected via a slaving element, for instance. 
         [0023]    In the case of articulated support, the pivot joint of the detent component can assume various positions relative to the detent element, which arrives in contact with the tightening neck, and to the actuation element, as long as a spacing both between the pivot joint and the detent element and between the pivot joint and the contact point between the actuation element and the detent component is assured. For instance, an arrangement in which the detent element is located between the pivot joint and the contact position with the actuation element can be considered. However, positioning the pivot joint between the detent element and the actuation element is also possible. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    The invention will be better understood and further objects and advantages thereof will become more apparent from the ensuing detailed description of preferred embodiments taken in conjunction with the drawings, in which: 
           [0025]      FIG. 1  is a section through an electric handheld power tool in an embodiment of the invention, of a ring-angle sander, in the region of the tool over which a guard hood fits that is retained on a tightening neck of the power tool; 
           [0026]      FIG. 2  shows the tightening neck and guard hood in a section perpendicular to the axis of the tool; 
           [0027]      FIG. 3  shows the securing device of the guard hood according to the invention, by way of which the guard hood is secured to the tightening neck, with a tightening ring, a screw tightening the tightening ring, and a detent component that is to be adjusted by the screw into a detent position; 
           [0028]      FIG. 4   a  shows a further securing device, in which the detent component has a modified embodiment; 
           [0029]      FIG. 4   b  shows a spring element which exerts force on the detent component of  FIG. 4   a;    
           [0030]      FIG. 5  shows a further securing device in an alternative embodiment; 
           [0031]      FIG. 6  shows a bearing flange with a tightening neck, in which a bearing for the tool is received, and a circumferential groove, with a set of teeth with which the detent component is to be put into the detent position, is made in the outer jacket face of the tightening neck; and 
           [0032]      FIG. 7 , similarly to  FIG. 6 , shows a bearing flange, but with a separate, axially offset embodiment of the circumferential groove and of a set of teeth extending over the circumference. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0033]    In the drawings, identical components are identified by the same reference numerals. 
         [0034]    The handheld power tool  1  shown in  FIG. 1  is embodied as a right-angle or cutting sander, which in a tightening neck  2  has a bearing  3  for rotationally supported reception of a drive spindle  4  that is the carrier of a tool  5  embodied as a sanding wheel or cutting wheel. The tool  5  is partly surrounded by a guard hood  6 , which has an integrally formed-on cylindrical collar  7  that is slipped onto the outside of the tightening neck  2 . The collar  7  is firmly clamped to the tightening neck  2  via a tightening ring  8  of a securing device; an additional detent component for securing in the circumferential direction and/or the axial direction is provided, and the detent component  9  protrudes through a recess in the collar  7  and into a toothlike indentation  10  that is made in the jacket face of the tightening neck  2 . 
         [0035]    As can be seen from  FIG. 2 , the tightening ring  8 , in a manner known per se, on its face ends has end portions  8   a ,  8   b  bent radially upward, in each of which a recess is made through which a screw  11  is passed that forms an actuation element. The screw is secured to the tightening ring via a nut, so that when the screw  11  is turned, the tightening ring  8  is tightened and presses against the tightening neck  2  with increasing, radially acting tightening force. 
         [0036]    The free face end  12  of the screw  11  is in contact with a portion of the detent component  9  that is to be put into a detent position by the tightening neck  2 . As can be seen from  FIG. 2  in conjunction with  FIG. 3 , the detent component  9  is embodied as a lever, and a detent element  13  is embodied in one piece with the detent component  9  and, compared to the approximately circumferentially extending base body of the detent component  9 , extends radially inward in the direction of the outer jacket face of the tightening neck  2 . A recess  14  is made in the tightening ring  8  and the detent element  13  protrudes through this recess. 
         [0037]    The base body of the detent component  9  is supported rotatably or pivotably via a pivot joint  15  on the side facing away from the screws  11  and at the same time is retained on the tightening ring  8 . The pivot joint  15  is located on the outside of the tightening ring  8  and is connected to the tightening ring  8 . A spring element can additionally be provided, which exerts force on the detent component  9  into the nondetent position, in which position the detent element  13  of the detent component  9  is at least partially raised out of the recess  14 . The pivot joint  15  enables the detent component  9  to execute a rotary motion about an axis that is parallel to the axis of rotation of the tool. 
         [0038]    On the side toward the actuation element, the base body of the detent component  9  has a contact portion  9   a , which is bent in hooklike fashion and is contact with the fee face end  12  of the actuation element that is embodied as a screw  11 . The hooklike contact portion  9   a  is embodied such that as the screw  11  is screwed increasingly in, the base body of the detent component  9  and thus the detent element  13  as well are adjusted into the detent position by way of the contact between the free face end  12  and the portion  9   a . The detent position is shown in bow  FIG. 2  and  FIG. 3 . If a spring element is provided that exerts force on the detent component  9  into the nondetent position, then a leg spring that is placed around the pivot joint  15  can for instance be employed. 
         [0039]    In the exemplary embodiment of  FIGS. 2 and 3 , the pivot joint  15  is located on the side facing away from the screw  11 . The detent element  13  on the detent component  9  is located between the pivot joint  15  and the contact point between the free face end  12  of the screw  11  and the hooklike contact portion  9   a  of the detent component  9 . 
         [0040]    Instead of a separately embodied spring element it is also possible to make the detent component  9  from a resilient material, such as spring steel, and to prestress it such that the detent component  9  in the mounted position is adjusted by its own tension into the nondetent position. This has the advantage that a spring element embodied as a separate component can be dispensed with. 
         [0041]    The detent component  9  has an end stop  23 , which originating at the pivot joint  15  is disposed on the side of the pivot joint remote from the actuation element embodied as a screw  11 . The end stop  23  has the function of limiting the upward pivoting motion of the detent component  9  about the axis of rotation of the pivot joint  15 . To that end, the end stop  23 , preferably embodied in one piece with the detent component, protrudes at an angle from the outside of the tightening ring  8 , and the angle with the outside of the tightening ring  8  defines the maximum upward pivoting angle of the detent component  9 . In the maximally upward-pivoted position, the end stop  23  rests on the outside of the tightening ring  8 . 
         [0042]    In the exemplary embodiment of  FIG. 4   a , the detent component  9  is shown in an alternative embodiment. The pivot joint  15  of the detent component  9  is located between the detent element  13  and the contact point on the free face end  12  of the actuation element. The base body of the detent component  9  is constructed in angular form, and the free face end, facing away from the pivot joint  15 , simultaneously forms the detent element  13 , which is passed through the recess  14  in the tightening ring  8 . Near the angular region in the base body, the free face end  12  of the screw  11  is in contact with the detent component  9 . 
         [0043]    In  FIG. 4   b , a spring element  16  embodied as a leg spring is shown in detail; it can be placed around the pivot joint  15  of  FIG. 4   a  and in the mounted position it exerts force on the detent component  9  into the nondetent position. 
         [0044]    In  FIG. 5 , a further exemplary embodiment is shown, in which it is fundamentally possible to dispense with a separate spring element that urges the detent component  9  into the nondetent position. The adjustment of the detent component  9  both from the nondetent position into the detent position and in the opposite direction, that is, from the detent position into the nondetent position, is effected via the adjusting motion of the actuation element embodied as a screw  11 . For that purpose, the screw  11  is connected in the region of its face end to the base body of the detent component  9  via a slaving element  17 . On the side opposite the slaving element  17 , there is a spring element  18 , which is embodied as a compression spring and presses the detent component  9  axially against the slaving element  17 . It is thus assured first that upon a screwing-in motion of the actuation element  11 , the detent component  9  is adjusted into the detent position, and second that with the aid of the spring element  18  and of the axial displacement motion of the detent component  9  on the actuation element, play and flexibility in the components can be compensated for. The detent element  13 , which in the detent position is in engagement with the set of teeth on the jacket face of the tightening neck, is as in the preceding exemplary embodiment embodied in one piece with the base body of the detent component  9 . 
         [0045]    The axial displacement capability of the detent component  9  along the axis of the screw  11  offers the farther advantage that upon a relative rotation of the tightening ring  8  clockwise in terms of  FIG. 5 , self-locking occurs, and hence the form lock between the detent component and the set of teeth on the tightening neck increases. In the opposite direction, conversely, the detent component can execute a relative motion because of the free travel on the actuation element, and as a result a limited play is achieved. 
         [0046]    In  FIG. 6 , a bearing flange  19  is shown, including a base plate  20  and the tightening neck  2  embodied in one piece with the base plate, the bearing  3  for the drive spindle  4  being received in this tightening neck. A set of teeth  21  is made in the outer jacket face of the tightening neck  2  and comprises a plurality of axially extending toothlike indentations, distributed over the circumference, which are associated with the detent element of the detent component; in the detent position, the detent element protrudes into a respective toothlike indentation. As a result, a form lock in both the circumferential direction and the axial direction is attained. 
         [0047]    The toothlike indentations each extend axially from a circumferential groove  22  that extends over the entire circumference of the tightening neck  2 . The detent element of the detent component can be displaced along the circumferential groove  22 . However, optionally, a component embodied separately from the detent element, such as a pin or the like, protrudes into the circumferential groove and thereby secures both the tightening ring and the guard hood in the axial direction on the tightening neck. 
         [0048]    In the exemplary embodiment of  FIG. 7 , which also shows a bearing flange  19  with a base plate  20  and a tightening neck  2 , the set of teeth  21  is embodied separately from the circumferential groove  22 . The set of teeth  21  is located adjacent to the top side of the base plate  20 ; conversely, the circumferential groove  22  is located adjacent the face end of the tightening neck  2 . In this embodiment, it is absolutely necessary that a component embodied separately from the detent component protrude into the circumferential groove  22 , this component for instance being a pin or the like. 
         [0049]    The foregoing relates to 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.