Electric motor/generator power transfer unit

A power transfer unit comprising:

• a differential gear set including a first input/output coupled to a first hydraulic rotating group, a second input/output coupled to a second hydraulic rotating group, and a third input/output coupled to an electric rotating group, wherein the first hydraulic rotating group is hydraulically coupled to a first hydraulic circuit, the second hydraulic rotating group is hydraulically coupled to a second hydraulic circuit, and the first hydraulic circuit is hydraulically separated from the second hydraulic circuit;
• a first mode wherein power is transferred through the differential gear set from the first hydraulic rotating group to the second hydraulic rotating group;
• and
• a second mode wherein power is transferred through the differential gear set from the electric rotating group to the first hydraulic rotating group.

A multi-mode electric motor/generator power transfer unit comprising:

• a differential gear set including a first input/output member, a second input/output member, and a third input/output member;
• a first pump/motor coupled to the first input/output member;
• a second pump/motor coupled to the second input/output member;
• an electric motor/generator coupled to the third input/output member;
• a first hydraulic circuit hydraulically coupled to the first pump/motor;
• a second hydraulic circuit hydraulically coupled to the second pump/motor;
• a power transfer unit mode wherein power is transferred through the differential gear set between the first pump/motor and the second pump/motor;
• and
• an electric motor/pump mode wherein power is transferred through the differential gear set between the electric motor/generator and at least one of the pump/motors.

A redundant hydraulic system with at least dual redundancy, the redundant hydraulic system comprising:

• a differential gear set including a first input/output member, a second input/output member, and a third input/output member;
• a first pump/motor coupled to the first input/output member;
• a second pump/motor coupled to the second input/output member;
• an emergency power supply coupled to the third input/output member;
• a first hydraulic circuit hydraulically coupled to the first pump/motor;
• and
• a second hydraulic circuit hydraulically coupled to the second pump/motor.