Abstract:
A side handle for a power tool comprising: a central bar; a tubular grip which is mounted on and surrounds the central bar via a vibration dampener; the vibration dampener comprising a spring having a central plate, which is mounted in a non moveable manner on the central bar, and a plurality of resiliently deformable arms attached to the plate and which extend away from the plate towards the grip, the ends of each of the arms being non moveably attached to the grip.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority, under 35 U.S.C. §119(a)-(d), to UK Patent Application No. GB 10 119 78.2 filed Jul. 15, 2010, the contents of which is incorporated herein by reference in its entirety. EP2082846 filed on Jan. 21, 2009 is also incorporated herein by reference in its entirety. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates to a side handle for a power tool, and in particular, to a side handle for a drill. 
       BACKGROUND OF THE INVENTION 
       [0003]    Drills, in particular, hammer drills, comprise a main housing in which is mounted a spindle and a motor, which rotatingly and/or axially drives the spindle via gears and/or a hammering mechanism, also located within the housing. The spindle transfers the rotational and/or axial movement of the spindle to a cutting tool, such as a drill bit, via a chuck or tool holder attached to the end of the spindle, forward of the main housing. Typically, such drills have two handles, a rear handle attached at the rear of the main housing and a side handle attached towards the front of the main housing, on one side of the main housing. Often, the side handle can be attached to either side of the main housing. 
         [0004]    One type of side handle comprises a hand grip which is attached at one end to a base, which is attached to the side of main housing, and which extends away from the base and the housing in a direction generally perpendicular to the longitudinal axis of the spindle of the drill. 
         [0005]    A problem with power tools, in particular drills, is that they generate a large amount of vibration during their operation. The transfer of the vibration from the tools to the hands of the operator can lead to injury to the hands of the operator and therefore it is desirable to minimise the amount of vibration transferred. One way of achieving this to provide a vibration dampener between the hand grip and the base to reduce the amount of vibration transferred from the base to the hand grip. 
         [0006]    EP2082846, as published, describes such a design of side handle for a drill in paragraphs 45 to 52 with reference to  FIGS. 7 to 13 . The side handle comprises a hand grip 84 (using the same reference numbers as EP2082846) which is attached to a bolt 106 via two vibration dampeners 118, 120. The bolt 106 attaches to a base 80. The dampeners 118, 120 are made from resilient rubber. During use of such a side handle, the operator applies pressure to the hand grip 84 in a direction generally parallel to the longitudinal axis of the spindle of the drill to which the handle is attached, which is perpendicular to longitudinal axis of the hand grip. As such, this applies a rotation force onto the hand grip 84 in a direction perpendicular to the longitudinal an axis of the hand grip about an axis of rotation located in close proximity to the base 80. This results in a large degree of sideways pressure being placed on the dampener 118 closest to the base 80, which, due to it being made from rubber, becomes compressed on one side. This reduces the performance of the vibration dampener 118. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    The present invention overcomes or at least reduces the problems associated the design of side handle disclosed in EP2082846. 
         [0008]    Accordingly, there is provided a side handle for a power tool comprising:
       a central bar;   a tubular grip which is mounted on and surrounds the central bar via a vibration dampener;   the vibration dampener comprising a spring having a central plate, which is mounted in a non moveable manner on the central bar, and a plurality of resiliently deformable arms attached to the plate and which extend away from the plate towards the grip, the ends of each of the arms being non moveably attached to the grip.       
 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    An embodiment of the present invention will now be described with reference to the accompanying drawings of which: 
           [0013]      FIG. 1  shows an exploded side view of a the side handle according to the present invention; 
           [0014]      FIG. 2  shows a perspective end view of the side handle (excluding the base); 
           [0015]      FIG. 3  shows a perspective end view of the side handle with the plastic cap in an exploded position; 
           [0016]      FIG. 4  shows a perspective end view of the side handle with the spring and plastic cap in an exploded position; 
           [0017]      FIG. 5  shows a cut away rear perspective view; and 
           [0018]      FIG. 6  shows a vertical cross sectional view. 
       
    
    
       [0019]    An embodiment of a side handle according to the present invention will now be described. The embodiment is for a side handle for a drill. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0020]    Referring to  FIG. 1 , the side handle comprises a plastic grip  1016  which is mounted on a bolt  1012  via a vibration dampening mechanism (as shown in  FIG. 5  and which is described in more detail below). The bolt  1012  has a threaded end  1019  which projects from the end of the grip  1016 . The side handle comprises a base  1050  and an attachment loop  1052 . The attachment loop  1052  comprises a flexible metal strip  1054  which is attached at both ends to a nut  1056  which has a threaded passage  1058  formed through it. The base  1050  has a curved support  1060  and a tubular passageway  1062  which passes through its length. In use, the metal strip  1054  is wrapped around the body of a drill (not shown). The nut  1056  is inserted into the tubular passage  1062  from the side of the base  1050  containing the curved support  1060 . The threaded end  1019  of the bolt  1012  is inserted into the other end of the tubular passage  1062  until it engages with the threaded passage  1058  of the nut  1056 . The bolt  1012  is then rotated using the hand grip  1016 , causing the threaded end  1019  of the bolt  1012  to screw into the threaded passage  1058  of the nut  1056 . As the threaded end  1019  of the bolt  1012  screws into the threaded passage  1058  of the nut  1056 , the nut  1056  is drawn towards the grip  1016 . This causes the nut  1056  and metal strip  1054  to be drawn into the tubular passage  1062 , resulting in it tightening around the body of the drill. Once the metal strip  1054  is wrapped tightly around the body of the drill, the grip  1016  is prevented from further rotation. At this point the curved support  1060  also abuts the side of the drill. The side handle is thereby secured to the drill. In order to release the side handle, the grip  1016  is rotated in the opposite direction, thereby unscrewing the threaded end  1019  of the bolt  1012  from the nut  1056 . The entrance  1064  of the tubular passage  1062  is tapered to facilitate the entry and exit of the nut  1056  and metal strip  1054  into the tubular passage  1062 . 
         [0021]    The vibration dampening mechanism will now be described with reference to  FIGS. 2 to 6 . The vibration dampening mechanism comprises a metal spring  1000 . The metal spring  1000  comprises six arms  1002  which are resiliently deformable and which are integrally formed with and extend from a central hexagonal plate  1004  in a symmetrical shape. Each arm  1002  is L shaped with the first part  1080  extending away from the plate  1004  in the plane of the plate  1004 . The second part  1082  extends at an angle to the first part. A circular aperture  1006  is formed through the plate  1004 . Formed on the bolt  1012  is a flange  1008  having two flat sides  1010  which extend tangentially to the longitudinal axis  1066  of the bolt  1012 . The spring  1000  is located on the circular shank of the bolt  1012  immediately behind the flange  1008 . The spring  1000  can freely rotate about the shank of the bolt  1012 . The ends of the arms  1002  are rigidly connected to the plastic grip  1016  using rivets. However it will be appreciated that the ends of the arms  1002  can be connected using other means such as glue or be encased within the wall of the grip  1016  which would be molded around the ends of the arms  1002 . 
         [0022]    The plastic cap  1014  comprises two clips  1015  and a recess  1068  which corresponds to the shape of the flange  1008  on the bolt  1012 . A circular aperture  1017  is formed through the base of the recess. The plastic cap is mounted on the shank of the bolt in front of the flange  1008 , the flange  1008  locating in the recess  1068  with the front end  1019  of shank passing through the aperture  1017 . The clips  1015  clip onto the edges of the plate  1004 , holding the plate  1004  against the rear side of the flange. By clipping the plate  1004  to the cap  1014 , both the spring  1000  and cap  1014  are locked onto the bolt  1012  around the flange  1008 . As the sides of the plate  1004  are straight, the clips  1015  prevent rotational movement between the cap  1014  and the plate  1004 . As the flange  1008  has flat sides  1010 , the flange  1008  can not rotate within the recess  1068  and therefore the cap  1014  can not rotate relative to the flange  1008  and bolt  1012 . Thus rotation of the flange  1008  results in rotation of the cap  1014 . This in turn results in the plate  1004  being prevented from rotating relative to the flange  1008  and bolt  1012 . As the cap  1014 , located on the bolt  1012  on one side of the flange  1008 , is clipped to the plate  1004 , located on the bolt  1012  on the other side of the flange  1008 , both the cap  1014  and plate  1004  are prevented from axially sliding along the bolt  1012 . 
         [0023]    The plastic grip  1016  can move relative to the bolt  1012  by the bending of the arms  1002 . The grip can move axially (Arrow A) relative to the bolt  1012  or rotationally (Arrow B) about the longitudinal axis  1066  of the bolt  1012  and perpendicularly (Arrows C and D) to longitudinal axis  1066  of the bolt  1012  due to the flexible nature of the arms  1002 . The arms  1002  absorb vibration, reducing the amount transferred from the bolt  1012  to the grip  1016 . However, the resilience of the arms  1012  is sufficient to support the pressure applied to the grip  1012  by the operator during use whilst reducing vibration. 
         [0024]    Formed on the inner walls  1020  of the grip  1016  are ribs  1022 . The ribs  1022  inside of the grip  1016  are located so that, when the grip  1016  is rotated about the longitudinal axis  1066  of the bolt  1012  relative to the plastic cap  1014  (by the bending of the arms  1002 ), the ribs  1022  would engage with the sides of the clips  1015 . When no pressure is applied to the grip  1016 , the ribs  1022  are located with a space between the ribs  1022  and the clips  1015 . In order to screw or unscrew the bolt  1012  from the nut  1056 , the user rotates the grip  1016 . Rotational movement of the grip  1016  is initially transferred to the bolt  1012  via the arms  1002  of the spring  1000 . If the bolt  1012  is held rigidly in the nut  1056 , rotation of the grip  1016  results in the arms  1002  bending. However, once grip  1016  has been rotated sufficiently relative to the bolt  1016 , the ribs  1022  engage with the sides of the clips  1015  of the cap  1014 , the subsequent rotational movement then being transferred via the ribs  1015  directly to the cap  1014  via the clips  1015 , and hence to the bolt  1016 . This prevents damage to arms  1002  as they are prevented from being bent too much. 
         [0025]    It will be appreciated that the design of the arms  1002  can arranged to alter the amount of resilience in the directions of Arrows A, B, C and D, or even prevent movement in any one of those directions. The use of L shaped arms is particular beneficial in providing sufficient resilience in the direction of Arrow C so that, when the operator applies pressure to the hand grip  1016  in a direction generally parallel to the longitudinal axis of a spindle of the drill to which the handle is attached, which is perpendicular to longitudinal axis of the grip  1016 , the arms  1002  provide sufficient support to the grip  1016  whilst providing good vibration dampening to the grip  1016 . 
         [0026]    Located at the far end of the bolt  1012  remote from the flange  1008 , is a second vibration dampener  1070 . The dampener  1070  has the same design as the second dampener 120 (using the same reference numbers as EP2082846) described in EP2082846.