Hybrid transmission with single planetary gear set and multiple operating modes

A powertrain comprising:

• an input member;
• an output member;
• a stationary member;
• a first and a second electric machine;
• a gear train operatively connecting the second electric machine with the output member;
• wherein the gear train is configured to reduce speed from the second electric machine to the output member;
• only a single planetary gear set having a first member, a second member, and a third member;
• wherein the first, the second, and the third members include a ring gear member, a sun gear member, and a carrier member that supports pinion gears that mesh with both the ring gear member and the sun gear member;
• a first, a second, a third, and a fourth selectively engageable torque-transmitting mechanism;
• wherein the first torque-transmitting mechanism is selectively engageable to operatively connect the second electric machine with the output member;
• wherein the second torque-transmitting mechanism is selectively engageable to operatively connect the second member with the output member such that the output member rotates commonly with the second member;
• wherein the third torque-transmitting mechanism is selectively engageable to operatively connect the third member to the stationary member;
• wherein the fourth torque-transmitting mechanism is selectively engageable to operatively connect the second member to the stationary member, neither of the electric machines being continuously operatively connected with the output member;
• wherein selective engagement of a different one or ones of the torque-transmitting mechanisms and selective operation of one or both electric machines establishes a series operating mode, an input-split operating mode, three electric-only operating modes, and two fixed gear operating modes between the input member and the output member.

A powertrain comprising:

• an engine;
• a hybrid transmission having:
• an input member;
• an output member;
• a stationary member;
• a first and a second electric machine;
• only a single planetary gear set having a first member, a second member, and a third member;
• wherein the first, the second, and the third members include a ring gear member, a sun gear member, and a carrier member that supports pinion gears that mesh with both the ring gear member and the sun gear member;
• a first, a second, a third, and a fourth selectively engageable torque-transmitting mechanism;
• wherein the first torque-transmitting mechanism is selectively engageable to operatively connect the second electric machine with the output member;
• wherein the second torque-transmitting mechanism is selectively engageable to operatively connect the second member with the output member such that the output member rotates commonly with the second member;
• wherein the third torque-transmitting mechanism is selectively engageable to operatively connect the third member to the stationary member;
• wherein the fourth torque-transmitting mechanism is selectively engageable to operatively connect the second member to the stationary member;
• wherein selective engagement of a different one or ones of the torque-transmitting mechanisms, selective operation of the engine, and selective operation of one or both electric machines establishes:
• a series operating mode in which the first and the fourth torque transmitting mechanisms are engaged, the engine is on, the first electric machine is operated as a generator, and the second electric machine is operated as a motor;
• an input-split operating mode in which the first and the second torque transmitting mechanisms are engaged, the first electric machine is operated as a motor or as a generator, and the second electric machine is operated as a motor or as a generator;
• an electric-only operating mode in which the first torque transmitting mechanism is engaged, the second electric machine is operated as a motor, and the first electric machine and the engine are off;
• and
• a fixed gear operating mode in which the second and the third torque-transmitting mechanisms are engaged, the engine is on, and the electric machines are off.