Patent Publication Number: US-2011073343-A1

Title: Electric power tool

Description:
FIELD OF THE INVENTION 
     The present invention relates to an electric power tool having a wireless communication function by which the work information on the content of works can be wirelessly communicated between the electric power tool and the outside. 
     BACKGROUND OF THE INVENTION 
     Conventionally, there is proposed an electric power tool that includes, as shown in  FIG. 4 , a housing  10  and a wireless communication device  24  arranged inside the housing  10 , the wireless communication device  24  having an antenna unit  30   a  for transmitting information, e.g., the fastening torque, to a controller for managing a screw tightening work, only the antenna unit  30   a  being arranged outside the housing (see, e.g., Japanese Patent Application Publication No. H06-312381). 
     Also proposed is an electric power tool that includes, as shown in  FIG. 5 , a housing  10  and a wireless communication device  24  arranged inside the housing  10 , the wireless communication device  24  having an antenna unit  30   a  stored in a rack  21  arranged outside the housing  10  (see, e.g., Japanese Patent Application Publication No. 2008-213069). 
     With the electric power tools cited above, there is a likelihood that the wireless communication device arranged inside the housing may collide with the surrounding structures due to the vibration generated during works and may eventually be broken. In addition, the electric power tools suffer from a problem in that those foreign materials such as iron particles or the like may accumulate on the antenna unit when the antenna unit is stored at the end of works, which may attenuate radio waves. 
     SUMMARY OF THE INVENTION 
     In view of the above, the present invention provides an electric power tool capable of preventing a wireless communication device from being broken due to the collision with the surrounding structures otherwise caused by vibration and also capable of preventing foreign materials such as iron particles or the like from accumulating on an antenna unit. 
     In accordance with an embodiment of the present invention, there is provided an electric power tool, including: a housing; a motor arranged within the housing; a power transmission unit arranged within the housing for transferring rotation of the motor to a work tool; a motor control unit arranged within the housing for controlling the rotation of the motor; a trigger switch provided to the housing for instructing the motor control unit to control the rotation of the motor; and a wireless communication device arranged within the housing for wirelessly communicating the work information on the content of works, the wireless communication device including an antenna unit, wherein the wireless communication device is covered with a shock-absorbing material, the antenna unit being arranged to lie higher than the trigger switch when the electric power tool is stored in a specified storage state. 
     With such configuration, by covering the wireless communication device with the shock-absorbing material, it becomes possible for the shock-absorbing material to reduce the shock applied to the wireless communication device when the latter collides with the surrounding structures due to the vibration generated during works. Further, since the antenna unit is arranged within the housing to lie higher than the trigger switch when the electric power tool is stored in a specified storage state, it is possible to prevent foreign materials, such as iron particles or the like, that have infiltrated through the gap between the trigger switch and the housing from accumulating on the antenna unit. 
     The specified storage state may be a state in which the electric power tool is stored in a tool folder such that an output portion thereof for holding the work tool faces obliquely downwards. 
     The present electric power tool can prevent the wireless communication device from being broken due to the collision with the surrounding structures otherwise caused by vibration and can also prevent those foreign materials such as iron particles or the like from accumulating on the antenna unit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The objects and features of the present invention will become apparent from the following description of embodiments, given in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a schematic explanation view showing an electric power tool in accordance with one embodiment of the present invention; 
         FIG. 2  is a schematic configuration view showing a wireless communication device employed in the electric power tool; 
         FIG. 3  is a schematic explanation view showing the electric power tool which is being stored out of works; 
         FIG. 4  is a side view illustrating a conventional electric power tool; and 
         FIG. 5  is a side view illustrating another conventional electric power tool. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     One embodiment of an electric power tool in accordance with the present invention will now be described with reference to the accompanying drawings which form a part hereof. 
     Referring to  FIG. 1 , an electric power tool  1   a  includes a hollow tubular grip  11  formed into a hand-held size and a hollow tubular body  12  provided at one axial end (upper end) of the grip  11 . The body  12  has an axis intersecting the axis of the grip  11  so that the body  12  and grip  11  can make a substantially “T”-shape when seen in a side view. The electric power tool  1   a  further includes a battery holder  13  provided at the other axial end (lower end) of the grip  11 . The grip  11 , the body  12  and the battery holder  13  make up a housing  10  of the electric power tool  1   a.  A rechargeable battery (not shown) is accommodated within the battery holder  13  removably attached to the lower end portion of the grip  11 . Electric power for operation of the electric power tool  1   a  is supplied from the rechargeable battery to a motor control unit  20  and a wireless communication device  24 , which will be described later, through power cords  26  and  31  respectively. Alternatively, the battery holder  13  may be integrally formed with the lower end portion of the grip  11 . 
     A metal-made cover  12   a  is arranged at one axial end (front end) side of the body  12 . Also arranged at the front end side of the body  12  is a metal-made chuck  15  to which a work tool (bit)  14  such as a driver bit or a socket is attached in a removable manner. The chuck  15  is rotationally driven about the axis of the body  12  by a motor  16  arranged at the other end (rear end) side of the body  12 . The rotational drive force of the motor  16  is transferred to the chuck  15  through a power transmission unit  17  built in the body  12 . 
     The power transmission unit  17  includes a speed reducer  17   a  connected at one end (rear end) to the motor  16  and an impact generating unit  17   b  connected to the other end (front end) of the speed reducer  17   a.  The rotational movement of the motor  16  is transferred at a reduced speed to the chuck  15  through the speed reducer  17   a  and the impact generating unit  17   b.  The speed-reduced rotational movement of the motor  16  is merely transferred to the chuck  15  insofar as the load applied to the chuck  15  is smaller than or equal to a specified value. If the load applied to the chuck  15  exceeds the specified value, the impact generating unit  17   b  makes impact applying movement by which an impulsive rotational drive force is transferred to the chuck  15 . 
     On the front surface of the upper end portion of the grip  11  on the side of the chuck  15 , a trigger switch  18  is provided retractably in the front-rear direction. The trigger switch  18  is pressed to variably control the rotational speed of the motor  16 . At the upper rear side of the trigger switch  18 , a forward-reverse changeover switch  19  for changing over the rotational direction of the motor to a forward direction or a reverse direction is arranged to protrude from the surface of the body  12 . The motor control unit  20  is accommodated in the inner upper portion of the grip  11  while the wireless communication device  24  is built in the inner lower portion of the grip  11 . 
     As shown in  FIG. 2 , a flexible antenna line  30  extends from the wireless communication device  24 . At the tip end of the antenna line  30 , there is arranged an antenna unit  30   a  for wirelessly communicating the work information on the content of works to an external management device (not shown). Since the antenna line  30  is formed into a string shape, the antenna unit  30   a  can be placed in any arbitrary empty position within the grip  11 . The wireless communication device  24  is provided with the power cord  31  connected to the rechargeable battery lying inside the battery holder  13 . Electric power for operation of the electric power tool is supplied from the rechargeable battery through the power cord  31 . In the present embodiment, the antenna unit  30   a  is arranged in the empty position between the speed reducer  17   a  of the power transmission unit  17  and the motor control unit  20  as shown in  FIG. 1 . 
     The wireless communication device  24  except those portions connected to the antenna line  30  and the power cord is fully covered with a shock-absorbing material  100 . This makes it possible for the shock-absorbing material  100  to reduce the shock applied to the wireless communication device  24  when the latter collides with the surrounding structures due to the vibration generated during works. Thus, the shock-absorbing material  100  protects the wireless communication device  24  from breakage. 
     A rack  21  is pivotally attached to the lower rear portion of the outer surface of the grip  11  so that it can rotate about a pivot shaft  22  in the front-rear direction. The rack  21  is in the shape of a rod and is pivotally supported at one end thereof by the pivot shaft  22  so that it can rotate from an angular position substantially perpendicular to the axial direction of the grip  11  to an angular position substantially parallel to the axial direction of the grip  11 . 
     A loop-shaped drop preventing strap  23  is attached to the lower rear portion of the grip  11 . 
     The on/off operation and rotation speed of the motor  16  are controlled by the motor control unit  20 . Depending on the retraction amount of the trigger switch  18  and responsive to the instruction of the trigger switch  18  to control the rotation speed of the motor  16 , the motor control unit  20  controls the motor  16 . In addition, the motor control unit  20  can change the direction of rotation of the motor  16  in response to the instruction of the forward-reverse changeover switch  19 , thereby determining whether to tighten or loosen a screw. The motor control unit  20  and the motor  16  are connected to each other by a connection line  27  so that the motor control unit  20  can control the motor  16  through the connection line  27 . Although not shown in the drawings, the motor control unit  20  is also connected to the trigger switch  18  and the forward-reverse changeover switch  19  so that it can control an output of the motor  16  in response to the signals inputted from the trigger switch  18  and the forward-reverse changeover switch  19 . 
     In the electric power tool  1   a,  the wireless communication device  24  transmits the work information on the content of works, such as the fastening torque, the number of screws tightened, the work time and the remaining battery level, to the external management device through the antenna unit  30   a.    
     When not in use, e.g., when a series of works is stopped or come to an end, the electric power tool  1   a  is held in a job-site tool folder  40  in a specified storage state, namely in such a state that the front portion of the body  12  of the electric power tool  1   a  (the output portion in which the chuck  15  is arranged) is inserted into a holding hole  40   a  of the tool folder  40  in a downwardly inclined posture (see  FIG. 3 ). 
     As described above, the antenna unit  30   a  is arranged in the empty position between the speed reducer  17   a  of the power transmission unit  17  and the motor control unit  20 . 
     As shown in  FIG. 3 , the antenna unit  30   a  is positioned higher than the trigger switch  18  when the electric power tool  1   a  is kept in the specified storage state. Accordingly, when electric power tool  1   a  is kept in a downwardly inclined state, it is possible to prevent foreign materials, such as iron particles or the like, that have infiltrated through the gap between the trigger switch  18  and the housing  10  from accumulating on the antenna unit  30   a.  This makes it possible to avoid the problem of radio waves being attenuated and data transmission being hindered by the foreign materials such as iron particles otherwise accumulated on the antenna unit  30   a.    
     While the electric power tool of the present embodiment described above includes the housing  10  in which the grip  11  and the body  12  make a substantially “T”-shape when seen in a side view, it is needless to say that the present invention may be applied to an electric power tool including a substantially “I”-shaped housing in which the body  12  and the grip  11  are arranged along a straight line. Although an impact driver has been described as an example of the electric power tool in the present embodiment, the electric power tool may be the one having other functions, e.g., an oil pulse impact driver or a driver with no impact function. 
     While the invention has, been shown and described with respect to the embodiments, it will be understood by those skilled in the art that various changes and modification may be made without departing from the scope of the invention as defined in the following claims.