Patent ID: 7192373

Claim:
An electrically variable transmission comprising: an input member to receive power from an engine; an output member; first and second motor/generators; not more than first and second differential gear sets each having first, second and third members, wherein said first, second, and third members comprise a ring gear, sun gear, and carrier, in any order; and wherein each of said first and second differential gear sets includes not more than one ring gear, not more than one carrier, and not more than one sun gear; 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; an interconnecting member continuously connecting said first member of said first gear set with said first member of said second gear set; said first motor/generator being continuously connected with a member of said first or second gear set; said second motor/generator being continuously connected with a member of said first or second gear set which is different from said member connected with said first motor/generator; a first torque transfer device selectively connecting a member of said first gear set with another member of said first or second gear set; a second torque transfer device selectively connecting a member of said second gear set with another member of said first or second 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; a third torque transfer device selectively grounding a member of said first or second gear set; and a fourth torque transfer device connected in parallel with said first or second motor/generator for braking rotation thereof; wherein said first, second, third and fourth torque transfer devices are engageable alone to provide an electrically variable transmission with a continuously variable range of speed ratios and in pairs to provide four fixed forward speed ratios.