Power tool

Abstract

It is an object of the invention to provide an effective technique for reducing the load of user's fingers in a power tool. A representative power includes a body, a tool bit, a driving means and a handgrip that extends from a grip proximal end on the side of the body to a grip distal end in a direction that crosses the axial direction of the tool bit. The power tool includes a holding optimization region that is arranged on the handgrip and shaped to match with the holding form of the fingers of the user when the user holds the handgrip. Specifically, the holding optimization region at least includes the rear end surface of the grip distal end region such that a normal on the rear end surface crosses an axis of the tool bit forward of the handgrip. As a result, according to the invention, the force of the user's fingers and palm on the handgrip can be optimized.

1 . A power tool, comprising: 
 a body,    a tool bit mounted to a tip end region of the body,    a driving mechanism housed within the body to drive the tool bit,    a handgrip that extends from a grip proximal end on the side of the body to a grip distal end in a direction that crosses the axial direction of the tool bit and    a holding optimization region that optimizes the force of the palm and fingers of the user on the handgrip, the holding optimization region being arranged on the handgrip and shaped to match with a holding form of the fingers of the user when the user holds the handgrip.    
   
   
       2 . The power tool as defined in  claim 1 , wherein on the rear end surface of the grip distal end region, the holding optimization region includes a region configured such that a normal on the rear end surface crosses an axis of the tool bit forward of the hand and 
 wherein, when the user performs an operation while pressing the power tool forward by hand, the direction of the pressing force applied from the palm to the rear end surface of the handgrip substantially coincides in said region with the direction of the normal on the rear end surface, whereby the pressing force of the user's hand is evenly exerted on the handgrip.    
   
   
       3 . The power tool as defined in  claim 2 , wherein the handgrip is configured such that said normal extends along a direction in which the forefinger extends when straightened from the grip holding position.  
   
   
       4 . The power tool as defined in  claim 1 , further comprising: 
 a trigger provided on a front portion of the handgrip and operated to start and stop the driving means and    a trigger front surface that is provided on the trigger and depressed by the user with the thick of the forefinger, wherein, on the trigger front surface, the holding optimization region includes a region configured such that a normal on the trigger front surface crosses an axis of the tool bit forward of the handgrip, and wherein, when the user performs an operation by depressing the trigger with the forefinger while holding the handgrip, the direction of depressing the trigger by the forefinger substantially coincides in said region with the direction of the normal on the trigger front surface, whereby the force of the user's fingers on the handgrip is optimized.    
   
   
       5 . The power tool as defined in  claim 1 , wherein, in the handgrip, the holding optimization region includes a region configured such that the handgrip has an oval section along the axial direction of the tool bit and such that said section has a maximum diameter portion of which both major axis and minor axis are maximum and a minimum diameter portion of which both major axis and minor axis am minimum, the maximum diameter portion being disposed between the grip proximal end and the grip distal end of the handgrip, the minimum diameter portion being disposed nearer to the grip distal end than the maximum diameter portion, and wherein the holding optimization region is configured such that a finger on the grip distal end side is able to grip the handgrip more securely than a finger on the grip proximal end side when the user performs an operation while holding the handgrip, whereby the pressing force of the users hand is evenly exerted on the handgrip.  
   
   
       6 . The power tool as defined in  claim 5 , wherein handgrips designed specifically for relatively big users are scaled up in the major and minor axes of the maximum and minimum diameter portions to about 106 to 110% or preferably about 108% of handgrips designed for relatively small users.  
   
   
       7 . The power tool as defined in clam  5 , wherein, in the handgrip, the holding optimization region is configured such that the maximum diameter portion is farmed in a region in which the middle finger or the third finger is positioned when holding the handgrip and the minimum diameter portion is formed in a region in which the little finger is positioned when holding the handgrip.  
   
   
       8 . The power tool as defined in  claim 1 , wherein, in the handgrip, the holding optimization region includes a region configured such that a connecting line that continuously and vertically connects vertexes on a side surface of the handgrip extends in the form of a letter S such that an upper end of the line is directed toward a rear end of the grip proximal end and a lower end of the line is directed toward a front end of the grip distal end, and wherein the vertexes of the handgrip side surface are snugly fitted into a concave portion formed in the users palm when the user performs an operation while holding the handgrip, whereby the pressing force of the user's band is evenly exerted on the handgrip.  
   
   
       9 . The power tool as defined in  claim 8 , wherein the handgrip is configured such that the connecting line extends substantially along a heart line or a head line of the palm of the user who is holding the handgrip.  
   
   
       10 . The power tool as defined in  claim 1 , further comprising a trigger that is provided on a front portion of the handgrip and operated to start and stop the driving means, and a trigger front surface that is provided on the trigger and depressed by the user with the thick of the forefinger, wherein the holding optimization region includes at least one of a first to a fourth regions, 
 the first region being configured on the rear end surface of the grip distal end region such that a normal on the rear end surface crosses an axis of the tool bit forward of the handgrip,    the second region being configured on the trigger front surface such that a normal on the trigger font surface crosses an axis of the tool bit forward of the handgrip,    the third region being configured in the handgrip such that the handgrip has an oval section along the axial direction of the tool bit and has a maximum diameter portion of which both major axis and minor axis in said section are maximum and a minimum diameter portion of which both major axis and minor axis in said section are minimum, the maximum diameter portion being disposed in a region of the handgrip between the grip proximal end and the grip distal end, the minimum diameter portion being disposed new to the grip distal end than the maximum diameter portion, and    the fourth region being configured in the handgrip such that a connecting line that continuously and vertically connects vertexes on a side surface of the handgrip extends in the form of a letter S such that an upper end of the line is directed toward a rear end of the grip proximal end and a lower end of the line is directed toward a front end of the grip distal end,    whereby the pressing force of the user's hand is evenly exerted on the handgrip.    
   
   
       11 . The power tool as defined in  claim 1 , further comprising an electric motor as the driving member and a battery removably attached to the grip distal end portion of the handgrip to supply current to the electric motor, wherein the battery has a housing that houses one or more cylindrical cells and the housing is placed outside a grip region below the grip distal end when the battery is in an attached state.