Hybrid electrically variable transmission with geared reverse mode using single motor/generator

A transmission for a vehicle with an engine comprising:

• an input member for receiving power from the engine;
• an output member;
• a motor/generator;
• a compound differential gear set having four gear elements operatively interconnected with one another;
• wherein said input member is operatively connectable with a first of said gear elements, said motor/generator is operatively connectable with a second of said gear elements;
• first and second transfer members continuously connected with said third and fourth gear elements respectively to partially form first and second power paths, respectively, between said differential gear set and said output member;
• a plurality of intermeshing gears including a first gear set operatively connectable using a selectively engagable torque-transmitting mechanism to provide a speed ratio for forward rotation between said first transfer member and said output member, and a second gear set operatively connectable using another selectively engagable torque-transmitting mechanism to provide a speed ratio for reverse rotation between said second transfer member and said output member;
• and
• wherein said speed ratio for forward rotation and said speed ratio for reverse rotation are such that when said torque-transmitting mechanisms are both engaged, said input member is stationary while rotation and speed of said output member are determined by rotation and speed of said motor/generator.

A method of operating a transmission having first and second power paths at least partially defined by first and second transfer shafts, each of said transfer shafts being operatively connectable to a countershaft via different sets of intermeshing gears establishing different gear ratios, wherein the transfer shafts and a transmission input member are each connected to different members of a differential gear set, the method comprising:

• slipping a first torque-transmitting mechanism connected to another member of the differential gear set to thereby alter a speed of rotation of the first transfer shaft;
• during said slipping, engaging a second torque-transmitting mechanism to connect a first gear for common rotation with the first transfer shaft to thereby transfer torque via said first power path through one of said sets of intermeshing gears;
• and
• during said slipping and after said engaging, disengaging a third torque-transmitting mechanism to disconnect a gear from common rotation with said second transfer shaft to thereby transfer torque via said second power path through another of said sets of intermeshing gears.