In-wheel motor drive device

An in-wheel motor drive device comprising:

• an electric motor part;
• a wheel bearing part;
• and
• a speed reducer part configured to decelerate a rotation of the electric motor part and transmit the rotation to the wheel bearing part,
• wherein
• the speed reducer part is a parallel shaft gear reduction mechanism having three or more axes, the parallel shaft gear reduction mechanism including an input shaft integrally rotating with a rotating shaft of the electric motor part and having an input gear, an output shaft integrally rotating with a rotating shaft of the wheel bearing part and having an output gear, and an intermediate shaft having an input-side intermediate gear that meshes with the input gear and an output-side intermediate gear that meshes with the output gear,
• the input gear, the output gear, the input-side intermediate gear, and the output-side intermediate gear are helical gears,
• the output gear and the output-side intermediate gear have a larger module than the input gear and the input-side intermediate gear,
• the input gear and the input-side intermediate gear have a larger twisting angle than the output gear and the output-side intermediate gear, and
• the output gear and the output-side intermediate gear have a larger effective tooth length than the input gear and the input-side intermediate gear.