Patent ID: 8721482

Claim:
A hybrid drive system comprising: an input member that is connected to an engine so that driving force is transmitted; an output member that is connected to a wheel so that driving force is transmitted; a first rotating electrical machine; a second rotating electrical machine; a power split device that performs a differential operation with at least three rotating elements including an input rotating element that is connected to the input member so that driving force is transmitted, a reaction force rotating element that is connected to the first rotating electrical machine so that driving force is transmitted, and an output rotating element that is connected to the output member so that driving force is transmitted; a reduction gear that performs a differential operation with at least four rotating elements including an input rotating element that is connected to the second rotating electrical machine so that driving force is transmitted, a stationary element that is held against rotation or selectively held against rotation, one of remaining rotating elements of the at least four rotating elements, other than the input rotating element and the stationary element, is a first output rotating element and another of the remaining rotating elements is a second output rotating element; and a control portion that selects an operating mode of the hybrid drive system, from among: a first split mode wherein a first decelerated rotation, from which rotation of the second rotating electrical machine is decelerated by the reduction gear, and driving force thereof are transmitted to the output rotating element of the power split device via the first output rotating element without going through the input rotating element of the power split device, and a second split mode wherein a second decelerated rotation, from which rotation of the second rotating electrical machine is decelerated by the reduction gear at a decelerated gear ratio that is larger than the first decelerated rotation, and driving force thereof are transmitted to the input rotating element of the power split device via the second output rotating element without going through the output rotating element of the power split device.