Patent ID: 7238131

Claim:
An electrically variable transmission comprising: an input member to receive power from an engine; an output member; first and second motor/generators; first, second and third differential gear sets each having first, second and third members; said input member being continuously connected with at least one member of said gear sets, and said output member being continuously connected with another member of said gear sets; a first interconnecting member continuously connecting said first member of said first gear set with said first member of said second gear set; a second interconnecting member continuously connecting said second member of said first gear set with said second member of said second gear set; a third interconnecting member continuously connecting said third member of said second gear set with said first member of said third gear set; said first motor/generator being continuously connected with said first or second interconnecting member, or with a member of said first gear set; said second motor/generator being continuously connected with said first, second or third interconnecting member, or with a member of said third gear set; a first torque transfer device selectively connecting a member of said first gear set with another member of said first, second, or third gear set; a second torque transfer device selectively connecting a member of said third gear set with another member of said first, second or third gear set, the pair of members connected by said second torque transfer device being different from the pair of members connected by said first torque transfer device; and a third torque transfer device selectively grounding a member of said third gear set; wherein said first, second and third torque transfer devices are engageable alone or in pairs to provide an electrically variable transmission with a continuously variable range of speed ratios and four fixed forward speed ratios.