Power tool

Abstract

A power tool includes a housing, a motor, a fan and a cyclone separation unit. The fan generates an air flow that flows in from first air inlets of the housing and passes through the housing. The cyclone separation unit has second air inlets arranged in a circumferential direction of the cyclone separation unit. The first and second air inlets are arranged apart from each other in an axial direction of the cyclone separation unit. A first dust collecting chamber is defined: (i) between the first air inlets and the second air inlets in the axial direction of the cyclone separation unit, and (ii) between an inner peripheral surface of the housing and the cyclone separation unit, and configured to collect dust by inertia force. A second dust collecting chamber is defined within the cyclone separation unit and configured to collect dust by centrifugal force.

1 . A power tool, which is configured to drive a tool accessory that is removably mounted thereto, comprising:
 a housing having first air inlets;   a motor that is housed in the housing;   a fan that is housed in the housing and configured to be rotated by the motor and generate an air flow that flows in from the first air inlets and passes through the inside of the housing; and   a cyclone separation unit that is housed in the housing and has second air inlets arranged in a circumferential direction of the cyclone separation unit;   wherein:   the first and second air inlets are arranged apart from each other in an axial direction of the cyclone separation unit,   a first dust collecting chamber is defined: (i) between the first air inlets and the second air inlets in the axial direction of the cyclone separation unit, and (ii) between an inner peripheral surface of the housing and the cyclone separation unit, and configured to collect dust by inertia force, and   a second dust collecting chamber is defined within the cyclone separation unit and configured to collect dust by centrifugal force.   
     
     
         2 . The power tool as defined in  claim 1 , wherein the housing has at least one first outlet that is arranged between the first air inlets and the second air inlets in the axial direction of the cyclone separation unit and communicates the inside and outside of the first dust collecting chamber. 
     
     
         3 . The power tool as defined in  claim 2 , wherein the at least one first outlet is arranged so as not to overlap the second air inlets. 
     
     
         4 . The power tool as defined in  claim 2 , wherein:
 a normal attitude of the power tool in use is defined relative to a direction of gravity, and   the at least one first outlet is formed to face in the direction of gravity when the power tool is in the normal attitude.   
     
     
         5 . The power tool as defined in  claim 2 , wherein:
 the power tool is a grinder,   the power tool further comprises a spindle configured to be rotationally driven by the motor around a drive axis that defines an up-down direction of the power tool, the spindle having a lower end part configured to removably hold the tool accessory,   the housing extends in a front-rear direction orthogonal to the up-down direction,   the housing is configured such that an auxiliary handle is removably mounted on right and left sides of the housing in a left-right direction orthogonal to the up-down direction and the front-rear direction, and   the at least one first outlet includes at least one of (i) a lower outlet opened downward in the housing, (ii) a left outlet opened to the left in the housing, and (iii) a right outlet opened to the right in the housing.   
     
     
         6 . The power tool as defined in  claim 1 , wherein:
 the power tool is a grinder,   the power tool further comprises a spindle configured to be rotationally driven by the motor around a drive axis that defines an up-down direction of the power tool, the spindle having a lower end part configured to removably hold the tool accessory,   the housing extends in a front-rear direction orthogonal to the up-down direction, and   the first air inlets are formed on right and left sides of the housing in a left-right direction orthogonal to the up-down direction and the front-rear direction.   
     
     
         7 . The power tool as defined in  claim 1 , further comprising a seal that is configured to seal a clearance between the housing and the cyclone separation unit on an opposite side of the first air inlets to the second air inlets in the axial direction of the cyclone separation unit. 
     
     
         8 . The power tool as defined in  claim 1 , wherein:
 the axial direction of the cyclone separation unit defines a front-rear direction of the power tool,   the first air inlets are arranged rearward of the second air inlets,   the cyclone separation unit includes: (i) an outer cylinder, (ii) an intermediate cylinder that is arranged radially inside of the outer cylinder and has a rear end located forward of a rear end of the outer cylinder, and (iii) an inner cylinder that is arranged radially inside of the intermediate cylinder and has a rear end located forward of the rear end of the intermediate cylinder,   the first dust collecting chamber is defined between the housing and the outer cylinder,   a dust separation chamber is defined between the intermediate cylinder and the inner cylinder and communicates with the first dust collecting chamber via the second air inlets, and   an exhaust passage is defined within the inner cylinder and communicates the dust separation chamber and the outside of the cyclone separation unit, and   the second dust collecting chamber is defined between the outer cylinder and the intermediate cylinder and communicates with the dust separation chamber.   
     
     
         9 . The power tool as defined in  claim 8 , wherein the cyclone separation unit is configured such that a first swirl flow is generated within the dust separation chamber and a second swirl flow is generated within the second dust collecting chamber. 
     
     
         10 . The power tool as defined in  claim 8 , wherein the second dust collecting chamber includes: (i) a rear dust collecting chamber that is defined behind the intermediate cylinder within the outer cylinder and communicates with the dust separation chamber, and (ii) a front dust collecting chamber that is defined between the outer cylinder and the intermediate cylinder in front of the rear dust collecting chamber and communicates with the rear dust collecting chamber. 
     
     
         11 . The power tool as defined in  claim 10 , wherein the front dust collecting chamber is configured to have a sectional area at least partially decreasing forward. 
     
     
         12 . The power tool as defined in  claim 8 , wherein the outer cylinder, the intermediate cylinder and the inner cylinder are separately formed and integrally connected to each other to form a single separation unit assembly. 
     
     
         13 . The power tool as defined in  claim 1 , wherein the cyclone separation unit is disposed in the housing so as to be removable from the housing. 
     
     
         14 . The power tool as defined in  claim 1 , wherein:
 the air flow generated by the fan is cooling air for cooling the motor, and   the motor is arranged downstream of the cyclone separation unit in a flow direction of the air flow.   
     
     
         15 . The power tool as defined in  claim 14 , wherein:
 the power tool is a grinder,   the power tool further comprises a spindle configured to be rotationally driven by the motor around a drive axis that defines an up-down direction of the power tool, the spindle having a lower end part configured to removably hold the tool accessory,   a rotational axis of the motor extends in a front-rear direction orthogonal to the drive axis,   the motor is arranged behind the spindle, and   the cyclone separation unit is arranged behind the motor.   
     
     
         16 . The power tool as defined in  claim 8 , wherein:
 the intermediate cylinder has a conical shape having a diameter gradually decreasing rearward, and   at least part of the outer cylinder has a circular cylindrical shape having a substantially uniform diameter.