Power tool

Abstract

A power tool comprising a rotary motor disposed in a housing, a transmission mechanism attached to the rotary shaft of the rotary motor and a fan disposed on the rotary motor. The housing near to the fan defines a first air discharge port. The housing outside the transmission mechanism defines a second air discharge port. An inner wall of the housing between the first air discharge port and the transmission mechanism forms an air baffle. Cooling air may flow from the air baffle to the second air discharge port outside the transmission mechanism to cool the transmission mechanism.

1 . A power tool comprising: 
 a housing;    a rotary motor disposed in the housing and having a rotary shaft;    a transmission mechanism in engagement with the rotary shaft;    a fan for generating an airflow mounted radially on the rotary motor, wherein the housing near to the fan defines a first air discharge port for discharging air at the end of a first flow path and wherein the housing in close proximity to the transmission mechanism defines a second air discharge port for discharging air at the end of a second flow path, wherein an air baffle between the first air discharge port and the transmission mechanism is adapted to direct air along the second flow path, wherein the air directed along the second flow path serves to cool the transmission mechanism in use.    
   
   
       2 . The power tool as defined in  claim 1  wherein the air baffle is an elongate interior wall of the housing.  
   
   
       3 . The power tool as defined in  claim 1  wherein the second air discharge port is disposed in the housing at a position effectively coincident with the intersection of the axis of the rotary motor and the axis of the transmission mechanism.  
   
   
       4 . The power tool as defined in  claim 1  wherein the second air discharge port is a plurality of discrete air vents which are disposed circumferentially in the housing in close proximity to the transmission mechanism.  
   
   
       5 . The power tool as defined in  claim 4  wherein the discrete air vents are substantially evenly disposed circumferentially in the housing in close proximity to the transmission mechanism.  
   
   
       6 . The power tool as defined in  claim 4  wherein the discrete air vents are disposed circumferentially in the housing in a plane containing the intersection of the axis of the rotary motor and the axis of the transmission mechanism.  
   
   
       7 . The power tool as defined in  claim 4  wherein the discrete air vents are disposed circumferentially in the housing in a plane substantially containing the axis of the air baffle.  
   
   
       8 . The power tool as defined in  claim 1  wherein the first discharge port is disposed in at least a part of a portion of the housing which is substantially coplanar with the fan.  
   
   
       9 . The power tool as defined in  claim 1  wherein the first air discharge port is disposed in at least a part of a portion of the housing which is substantially coaxial with the fan.  
   
   
       10 . The power tool as defined in  claim 1  wherein the first air discharge port skirts the fan.  
   
   
       11 . The power tool as defined in  claim 1  wherein the transmission mechanism comprises: 
 a rotary gear wheel intermeshed with the rotary shaft; and    an elongate output shaft extending from the rotary gear wheel to a cutting element.    
   
   
       12 . The power tool as defined in  claim 11  wherein the elongate output shaft is downstream from the rotary gear wheel in the second flow path.  
   
   
       13 . The power tool as defined in  claim 11  wherein the second air discharge port is disposed in at least a part of a portion of the housing which is substantially coplanar with the elongate output shaft.  
   
   
       14 . The power tool as defined in  claim 11  wherein the second air discharge port is disposed in at least a part of a portion of the housing which is substantially coaxial with the elongate output shaft.  
   
   
       15 . The power tool as defined in  claim 11  wherein the second air discharge port skirts the elongate output shaft.