Portable power working machine

1. A portable power working machine, comprising:

a pipe-shaped operating arm;

a drive shaft extending through the operating arm;

an actuating part provided at a distal end of the operating arm and driven by rotation of an electric motor through the drive shaft, the electric motor being disposed at a proximal end of the drive shaft;

shoulder carrying means disposed near a proximal end of the operating arm;

a motor housing connected to the proximal end of the operating arm at a front end thereof and including a tubular peripheral portion extending in a direction in which the operating arm extends, and a rear side portion closing a rear end of the tubular peripheral portion, a peripheral portion having an inlet for cooling air at a front side thereof and an outlet at a rear side thereof; and

a drive unit including the electric motor, a cooling fan, and a heat sink, the electric motor being disposed near the front end of the motor housing and including a cylindrical stator, an electric motor cover attached to the stator and an output shaft projecting forward and rearward from the electric motor cover, the cooling fan being provided at a rear end of the output shaft, the heat sink being disposed between the electric motor cover and the cooling fan so as to extend from the electric motor cover and facing an inner surface of the peripheral portion with a gap therebetween,

wherein the drive unit is disposed in the motor housing with a gap provided between the drive unit and the peripheral portion such that the stator corresponds to the inlet, the cooling fan corresponds to the outlet, and the heat sink faces the inner surface of the peripheral portion,

wherein a front end of the output shaft is connected to the drive shaft for transferring power to the drive shaft, and

wherein a cooling-air passage is provided between the motor housing and the drive unit for guiding the cooling air from the inlet to the outlet through the cooling fan.

2. A portable power working machine, comprising:

an operating arm;

a drive shaft extending through the operating arm;

a motor housing connected to a proximal end of the operating arm at a front end thereof;

an actuating part attached to a distal end of the operating arm; and

a drive unit disposed in the motor housing, the drive unit driving the actuating part through the drive shaft,

wherein the motor housing has an inlet for cooling air at a position near a front end thereof and an outlet for the cooling air at a position near a rear end opposite to the front end thereof,

wherein the drive unit includes an electric motor disposed near the front end of the motor housing, a cooling fan disposed near the rear end of the motor housing and connected to an output shaft of the electric motor, and a heat sink disposed between the cooling fan and the electric motor so as to extend from the electric motor, and

wherein the cooling air drawn into the motor housing through the inlet in the motor housing by the cooling fan is guided through a gap between the drive unit and an inner surface of the motor housing and is discharged to the outside through the outlet in the motor housing.

3. The portable power working machine according to clam 2 , wherein the electric motor includes a stator and an electric motor cover, and has a cooling-air introduction opening provided between the stator and the electric motor cover and a cooling-air discharge opening provided in the electric motor cover at a position near the rear end of the motor housing, and

wherein the cooling air drawn into the motor housing through the inlet in the motor housing by the cooling fan is guided into the electric motor through the cooling-air introduction opening and out of the electric motor through the cooling-air discharge opening, and is discharged to the outside through the outlet in the motor housing.

4. The portable power working machine according to claim 1 , wherein the heat sink is disposed near the inlet in the motor housing.

5. The portable power working machine according to claim 2 , wherein the heat sink is disposed near the inlet in the motor housing.

6. The portable power working machine according to claim 1 , wherein the inlet in the motor housing has a cooling air guide that guides the cooling air in the circumferential direction of the output shaft.

7. The portable power working machine according to claim 2 , wherein the inlet in the motor housing has a cooling air guide that guides the cooling air in the circumferential direction of the output shaft.

8. The portable power working machine according to claim 2 , further comprising a shoulder carrying member at a position near the proximal end of the operating arm.

9. The portable power working machine according to claim 1 , wherein the actuating part is a cutting blade that is rotated by the rotation of the drive shaft.

10. The portable power working machine according to claim 2 , wherein the actuating part is a cutting blade that is rotated by the rotation of the drive shaft.