Technique for dissipating heat in electric work machine

An electric work machine comprising:

• an electric power input terminal configured to receive an AC power;
• a motor configured to be driven with the AC power received through the electric power input terminal;
• a mounting part (i) configured to be detachably attached to a tool or (ii) fixed to the tool, the mounting part being configured to transmit a rotational force of the motor to the tool;
• a circuit board including:
• a first surface, and
• an electronic circuit on the first surface, the electronic circuit being configured to control supply of the AC power to the motor, the electronic circuit including an electronic component configured to generate a Joule heat;
• a first heat dissipation plate spaced from the first surface by a first distance in parallel to the first surface;
• and
• a second heat dissipation plate spaced from the first surface by a second distance in parallel to the first surface, the second distance being smaller than the first distance, and the second heat dissipation plate being (i) thermally coupled with the first heat dissipation plate and (ii) configured such that no portion of the second heat dissipation plate faces the first heat dissipation plate along a direction perpendicular to the first surface;
• and
• a third heat dissipation plate spaced from the first surface by a third distance in parallel to the first surface, the third distance being greater than the second distance, the third heat dissipation plate (i) being thermally coupled with the second heat dissipation plate and (ii) including a first part facing the second heat dissipation plate along the direction perpendicular to the first surface.

A method for dissipating a heat generated in an electric work machine, the method comprising:

• providing a first heat dissipation plate in parallel to a first surface of a circuit board of the electric work machine such that the first heat dissipation plate is spaced from the first surface by a first distance;
• providing a second heat dissipation plate in parallel to the first surface such that the second heat dissipation plate is (i) spaced from the first surface by a second distance smaller than the first distance, (ii) thermally coupled with the first heat dissipation plate, and (iii) configured such that no portion of the second heat dissipation plate faces the first heat dissipation plate along a direction perpendicular to the first surface;
• and
• providing a third heat dissipation plate spaced from the first surface by a third distance in parallel to the first surface, the third distance being greater than the second distance, the third heat dissipation plate (i) being thermally coupled with the second heat dissipation plate and (ii) including a first part facing the second heat dissipation plate along the direction perpendicular to the first surface.