Hybrid transmission with synchronous shift between series and compound-split operating modes

1. A hybrid transmission operatively connected with an engine, comprising:

an input member operatively connected with the engine;

an output member;

a plurality of selectively engageable torque-transmitting mechanisms;

a gearing arrangement;

first and second motor/generators operatively connected with the gearing arrangement;

wherein a first of the torque-transmitting mechanisms is engaged to establish a hybrid series operating mode between the input member and the output member;

wherein only a second of the torque-transmitting mechanisms is engaged to establish a compound-split operating mode between the input member and the output member;

wherein a shift between the hybrid series operating mode and the compound-split operating mode is synchronous without slipping the torque-transmitting mechanisms;

wherein the gearing arrangement includes multiple planetary gear sets, each planetary gear set having multiple gear members; wherein powerflow from a first group of the gear members to a second group of the gear members is via an electrical path through the motor/generators in the series operating mode; and wherein powerflow from the first group of gear members to the second group of gear members is via a mechanical path established by engaging the second torque-transmitting mechanism in the compound-split operating mode;

wherein the planetary gear sets include a first, a second and a third planetary gear set; wherein the input member is connected for common rotation with a first member of the first planetary gear set; wherein the first motor/generator is connected for common rotation with a second member of the first planetary gear set and with a first member of the second planetary gear set; wherein the third member of the first planetary gear set is selectively grounded to the stationary member by engagement of the first torque-transmitting mechanism and is continuously connected for common rotation with the first member of the third planetary gear set;

wherein the second motor/generator is continuously connected for common rotation with the second member of the second planetary gear set and with the second member of the third planetary gear set; wherein the output member is continuously connected for common rotation with the third member of the third planetary gear set; and wherein the second torque-transmitting mechanism is selectively engageable to connect the third member of the second planetary gear set for common rotation with the interconnected third member of the first planetary gear set and first member of the third planetary gear set.

2. The hybrid powertrain of claim 1 , wherein the plurality of selectively engageable torque-transmitting mechanisms includes only the first and the second torque-transmitting mechanisms.

3. The hybrid powertrain of claim 1 , wherein the first member of the first planetary gear set is a ring gear member, the second member of the first planetary gear set is a sun gear member, and the third member of the first planetary gear set is a carrier member; and wherein the first member of the third planetary gear set is a ring gear member, the second member of the third planetary gear set is a sun gear member, and the third member of the third planetary gear set is a carrier member.

4. The hybrid powertrain of claim 3 , wherein the first member of the second planetary gear set is a ring gear member, the second member of the second planetary gear set is a sun gear member, and the third member of the second planetary gear set is a carrier member.

5. The hybrid powertrain of claim 3 , wherein the first member of the second planetary gear set is a sun gear member, the second member of the second planetary gear set is a ring gear member, and the third member of the second planetary gear set is a carrier member.

6. The hybrid powertrain of claim 1 , wherein the first member of the first planetary gear set is a carrier member, the second member of the first planetary gear set is a ring gear member, and the third member of the first planetary gear set is a sun gear member; wherein the first member of the second planetary gear set is a sun gear member, the second member of the second planetary gear set is a ring gear member, and the third member of the second planetary gear set is a carrier member; and wherein the first member of the third planetary gear set is a carrier member, the second member of the third planetary gear set is a sun gear member, and the third member of the third planetary gear set is a ring gear member.

7. The hybrid powertrain of claim 1 , wherein the first member of the first planetary gear set is a carrier member, the second member of the first planetary gear set is a sun gear member, and the third member of the first planetary gear set is a ring gear member; wherein the first member of the of the second planetary gear set is a sun gear member, the second member of the second planetary gear set is a carrier member, and the third member of the second planetary gear set is a ring gear member; and wherein the first member of the third planetary gear set is a carrier member, the second member of the third planetary gear set is a sun gear member, and the third member of the third planetary gear set is a ring gear member.

8. The hybrid powertrain of claim 1 , wherein the first motor/generator is operable to start the engine when the first torque-transmitting mechanism is engaged and the second torque-transmitting mechanism is not engaged.

9. A hybrid transmission operatively connected with an engine, comprising:

an input member operatively connected with the engine;

an output member;

a stationary member;

a first and a second selectively engageable torque-transmitting mechanism;

a first, a second and a third planetary gear set, each having a first member, a second member and a third member; wherein the transmission has no other planetary gear sets;

first and second motor/generators;

wherein the input member is connected for common rotation with a first member of the first planetary gear set; wherein the first motor/generator is connected for common rotation with a second member of the first planetary gear; wherein the third member of the first planetary gear set is selectively grounded to the stationary member by engagement of the first torque-transmitting mechanism;

wherein the second motor/generator is continuously connected for common rotation with the second member of one the second and the third planetary gear set; wherein the output member is continuously connected for common rotation with the third member of the third planetary gear set;

a first interconnecting member continuously connecting the second member of the first planetary gear set for common rotation with the first member of the second planetary gear set;

a second interconnecting member continuously connecting the third member of the first planetary gear set for common rotation with the first member of the third planetary gear set;

a third interconnecting member continuously connecting the second member of the second planetary gear set for common rotation with one of the second and the third member of the third planetary gear set;

wherein the first torque-transmitting mechanism is selectively engageable to ground the third member of the first planetary gear set to the stationary member;

wherein the second torque-transmitting mechanism is selectively engageable to connect the third member of the second planetary gear set for common rotation with the second interconnecting member;

wherein the first torque-transmitting mechanism is engaged to establish a hybrid series operating mode between the input member and the output member;

wherein the second torque-transmitting mechanism is engaged to establish a compound-split operating mode between the input member and the output member; and

wherein a shift between the hybrid series operating mode and the compound-split operating mode is synchronous without slipping the torque-transmitting mechanisms.

10. The hybrid transmission of claim 9 , wherein the first member of the first planetary gear set is a ring gear member, the second member of the first planetary gear set is a sun gear member, and the third member of the first planetary gear set is a carrier member; and wherein the first member of the third planetary gear set is a ring gear member, the second member of the third planetary gear set is a sun gear member, and the third member of the third planetary gear set is a carrier member.

11. The hybrid transmission of claim 9 , wherein the first member of the second planetary gear set is a ring gear member, the second member of the second planetary gear set is a sun gear member, and the third member of the second planetary gear set is a carrier member.

12. The hybrid transmission of claim 9 , wherein the first member of the second planetary gear set is a sun gear member, the second member of the second planetary gear set is a ring gear member, and the third member of the second planetary gear set is a carrier member.

13. The hybrid transmission of claim 9 , wherein the first member of the first planetary gear set is a carrier member, the second member of the first planetary gear set is a ring gear member, and the third member of the first planetary gear set is a sun gear member; wherein the first member of the of the second planetary gear set is a sun gear member, the second member of the second planetary gear set is a ring gear member, and the third member of the second planetary gear set is a carrier member; and wherein the first member of the third planetary gear set is a carrier member, the second member of the third planetary gear set is a sun gear member, and the third member of the third planetary gear set is a ring gear member.

14. The hybrid transmission of claim 9 , wherein the first member of the first planetary gear set is a carrier member, the second member of the first planetary gear set is a sun gear member, and the third member of the first planetary gear set is a ring gear member; wherein the first member of the of the second planetary gear set is a sun gear member, the second member of the second planetary gear set is a carrier member, and the third member of the second planetary gear set is a ring gear member; and wherein the first member of the third planetary gear set is a carrier member, the second member of the third planetary gear set is a sun gear member, and the third member of the third planetary gear set is a ring gear member.

15. A hybrid transmission operatively connected with an engine, comprising:

an input member operatively connected with the engine;

an output member;

a stationary member;

only two selectively engageable torque-transmitting mechanisms;

a gearing arrangement including nine rotatable gear elements;

first and second motor/generators; wherein the first motor/generator is continuously connected for common rotation with a first and a second of the nine gear elements;

wherein the second motor/generator is continuously connected for common rotation with at least one of a third and a fourth of the nine gear elements; wherein the input member and the output member are continuously connected for common rotation with a fifth and a sixth of the nine gear elements, respectively; wherein the fifth and the sixth of the nine gear elements are not continuously for common rotation with either of the motor/generators;

wherein a first of the torque-transmitting mechanisms is engaged to connect a seventh and an eighth of the nine gear elements to the stationary member to establish a hybrid series operating mode between the input member and the output member;

wherein a second of the torque-transmitting mechanisms is engaged to connect a ninth of the gear elements for common rotation with the seventh and the eighth gear elements to establish a compound-split operating mode between the input member and the output member; and

wherein a shift between the hybrid series operating mode and the compound-split operating mode is synchronous without slipping the torque-transmitting mechanisms.