US 9,808,872 B2
Portable electric cutter
Hayato Yamaguchi, Hitachinaka (JP); Hideyuki Tanimoto, Hitachinaka (JP); Kenichirou Yoshida, Hitachinaka (JP); and Shinji Kuragano, Hitachinaka (JP)
Assigned to HITACHI KOKI CO., LTD., Tokyo (JP)
Appl. No. 14/379,184
Filed by HITACHI KOKI CO., LTD., Tokyo (JP)
PCT Filed Mar. 13, 2013, PCT No. PCT/JP2013/001653
§ 371(c)(1), (2) Date Aug. 15, 2014,
PCT Pub. No. WO2013/136788, PCT Pub. Date Sep. 19, 2013.
Claims priority of application No. 2012-059182 (JP), filed on Mar. 15, 2012.
Prior Publication US 2015/0026985 A1, Jan. 29, 2015
Int. Cl. B23D 45/16 (2006.01); B25F 5/00 (2006.01)
CPC B23D 45/16 (2013.01) [B25F 5/008 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A portable electric cutter comprising:
a motor;
a circular saw blade driven to rotate by the motor;
a base having an upper surface and a bottom surface which is opposite to the upper surface and is slidable on a material to be cut, and having an opening through which the circular saw blade protrudes downward from the bottom surface;
a housing, disposed on the upper surface of the base, including a motor casing for accommodating the motor, the motor casing extending beyond an edge of the base in a first direction perpendicular to, and away from a circular surface of the circular saw blade;
a saw cover attached to the housing, the saw cover covering a part of the circular saw blade;
a handle integrated with or coupled to the housing, the handle extending over the housing in a second direction parallel with the circular surface of the circular saw blade, the handle being arranged in the first direction between the circular saw blade and the motor;
a fan which is disposed between the motor and the saw cover and which is driven by the motor to generate an air flow for cooling the motor, the circular saw blade, the fan, and the motor being arranged in that order in the first direction;
a driving circuit including switching elements for switching power supplied to the motor;
a control circuit for controlling the driving circuit; and
a circuit board on which both of the driving circuit and the control circuit are mounted, wherein:
the housing includes a circuit board casing for accommodating the circuit board, the circuit board casing being disposed between the base and the handle and extending toward the circular saw blade, at least a part of the circuit board casing is disposed closer to the circular saw blade than any part of blades of the fan,
the motor casing has motor cooling air vents,
the circuit board casing has circuit board cooling air vents,
the housing includes a space serving as an air flow path which communicates between the motor casing and the circuit board casing,
the circuit board is disposed in a flow path of the fan air,
at least a part of the circuit board is disposed closer to the circular saw blade than any part of the blades of the fan,
the motor is a brushless motor,
a rotation state detector for generating a signal in accordance with a rotation position of the motor is further provided, and
the control circuit receives the signal of the rotation state detector and transmits a signal for controlling the drive of the motor to the driving circuit.