Differential assembly

A differential assembly, comprising:

• a first rotary shaft and a second rotary shaft extending coaxially along a common rotational center axis while being allowed to rotate relatively to each other;
• and
• a differential mechanism that allows the first rotary shaft and the second rotary shaft to rotate at different speeds,
• wherein the differential mechanism comprises
• a first gear that is arranged around the rotational center axis to be rotated relatively to the first rotary shaft,
• a second gear that is arranged around the rotational center axis to be rotated relatively to the second rotary shaft and integrally with the first gear,
• a first eccentric gear that is arranged around a first eccentric axis offset from the rotational center axis while being meshed with the first gear, in such a manner as to rotate around the first eccentric axis and revolve around the rotational center axis,
• a second eccentric gear that is arranged around a second eccentric axis offset from the rotational center axis while being meshed with the second gear, in such a manner as to rotate around the second eccentric axis and revolve around the rotational center axis,
• a supporting member that is arranged around the rotational center axis to support the first eccentric gear and the second eccentric gear in a revolvable manner around the rotational center axis, while being allowed to rotate relatively to the first rotary shaft and the second rotary shaft,
• a first motion translating mechanism that translates a revolving motion of the first eccentric gear into a rotary motion of the first rotary shaft, and translates the rotary motion of the first rotary shaft into the revolving motion of the first eccentric gear, and
• a second motion translating mechanism that translates a revolving motion of the second eccentric gear into a rotary motion of the second rotary shaft, and translates the rotary motion of the second rotary shaft into the revolving motion of the second eccentric gear, and
• the first gear includes an internal gear,
• the first eccentric gear includes an external gear that is meshed with the first gear from radially inner side,
• the second gear includes an external gear,
• the second eccentric gear includes an internal gear that is meshed with the second gear contacted thereto from radially inner side,
• a gear ratio between the first gear and the first eccentric gear and a gear ratio between the second gear and the second eccentric gear are set to different values, and
• the first rotary shaft and the second rotary shaft are rotated in opposite directions when rotated at different speeds.