US Patent 7147582 Power transmission device

It is an object to obtain a power transmission device capable of allowing conflicting needs to coexist rationally and effectively in accordance with a driving situation. As powertransmitting mechanisms of a power transmission device, there are provided a plurality of characteristically-differentiated internally meshing planetary gear mechanisms, each having an external gear and an internal gear having external teeth and internal teeth the difference in the number of teeth between which is slight. In this structure, at least two of the internally meshing planetary gear mechanisms are disposed in parallel on a path of power transmission, and power transmission characteristics of the two mechanisms are designed to differ from each other.