Patent ID: 7905806

Claim:
A power train having dual modes for hybrid electric vehicles, comprising: an engine; a first planetary gear set provided with a first carrier directly and permanently coupled to the engine; a second planetary gear set having a second sun gear; a third planetary gear set having a third ring gear; a first clutch directly coupled between the second sun gear of the second planetary gear set and the third ring gear of the third planetary gear set to couple or decouple the second sun gear of the second planetary gear set to or from the third ring gear of the third planetary gear set; a second clutch to convert the third ring gear of the third planetary gear set between a stationary state and a rotatable state; a first motor generator directly and permanently coupled to either a third sun gear or a third carrier of the third planetary gear set; and a second motor generator directly coupled to one of either a first sun gear of the first planetary gear set or the second sun gear of the second planetary gear set, wherein one element of either the first planetary gear set or the second planetary gear set is coupled to a drive wheel without connection to any other planetary gear set, two elements of the first planetary gear set are directly coupled to two respective elements of the second planetary gear set, a remaining one of the third sun gear and the third carrier of the third planetary gear set which is not coupled to the first motor generator is coupled to one of the elements of the first planetary gear set and the second planetary gear set.