Abstract: A power transmission system of a hybrid electric vehicle may include an engine being a power source, a torque transmission device including four rotation shafts and a compound planetary gear set, the torque transmission device converting torque input from the engine, and outputting a converted torque, two supplemental power sources respectively connected to two rotation shafts among the four rotation shafts of the torque transmission device and supplying generated torque to the torque transmission device, two friction members selectively connecting two rotation shafts among the four rotation shafts of the torque transmission device to a transmission housing, an output device outputting torque transmitted from the torque transmission device, and a final reducing device decelerating torque transmitted from the output device and outputting the decelerated torque through a differential apparatus.

Abstract: A transmission system of a hybrid electric vehicle may include a first shaft connected to an engine, a first hollow shaft disposed without rotational interference with the first shaft and provided with a first output gear, a second hollow shaft disposed without rotational interference with the first hollow shaft and provided with a second output gear, a second shaft disposed in parallel with the first shaft and operably connected to the first shaft and the first hollow shaft through a gear unit so as to selectively transmit torque of the first shaft to the first hollow shaft, a clutch selectively connecting the second shaft to the first hollow shaft, a first motor/generator operably connected to the second hollow shaft, and a second motor/generator operably connected to the second shaft.

Abstract: A transmission system of a hybrid electric vehicle may include two shafts, two hollow shafts and two motor/generators. A first shaft connected to an engine. A first hollow shaft disposed without rotational interference with the first shaft, selectively connected to the first shaft, and provided with a first output gear. A second hollow shaft disposed without rotational interference with the first hollow shaft and provided with a second output gear. A second shaft disposed in parallel with the first shaft and operably connected to the first shaft and the first hollow shaft through a gear unit to selectively transmit torque of the first shaft to the first hollow shaft. Clutches may connect the first shaft and the second shaft selectively to the first hollow shaft. A first motor/generator operably connected to the second hollow shaft and a second motor/generator operably connected to the second shaft.

Abstract: A transmission system of a hybrid electric vehicle may include a first shaft connected to an engine, a first hollow shaft disposed without rotational interference with the first shaft, selectively connected to the first shaft, and provided with a first output gear, a second hollow shaft disposed without rotational interference with the first hollow shaft and provided with a second output gear, a second shaft disposed in parallel with the first shaft and connected to the first shaft through a gear unit, a clutch selectively connecting the first shaft to the first hollow shaft, a first motor/generator operably connected to the second hollow shaft, and a second motor/generator operably connected to the second shaft.

Abstract: A power transmission system of a hybrid electric vehicle may include an input shaft receiving torque of an engine, a first planetary gear set having at least three rotation elements, a second planetary gear set having at least three rotation elements, a clutch selectively connecting two rotation elements among the at least three rotation elements of the second planetary gear set, a brake selectively connecting a rotation element of the second planetary gear set to the transmission housing, and an output gear connected to a second motor/generator and the a rotation element of the second planetary gear set.

Abstract: A transmission system of a hybrid electric vehicle may include a first shaft connected to an engine, a first hollow shaft disposed without rotational interference with the first shaft, selectively connected to the first shaft, and provided with a first output gear, a second hollow shaft disposed without rotational interference with the first hollow shaft and provided with a second output gear, a second shaft disposed in parallel with the first shaft and connected to the first shaft through a gear unit, a clutch selectively connecting the first shaft to the first hollow shaft, a first motor/generator operably connected to the second hollow shaft, and a second motor/generator operably connected to the second shaft.

Abstract: A power transmission system of a hybrid electric vehicle may include an engine being a power source, a torque transmission device including four rotation shafts and a compound planetary gear set, the torque transmission device converting torque input from the engine, and outputting a converted torque, two supplemental power sources respectively connected to two rotation shafts among the four rotation shafts of the torque transmission device and supplying generated torque to the torque transmission device, two friction members selectively connecting two rotation shafts among the four rotation shafts of the torque transmission device to a transmission housing, an output device outputting torque transmitted from the torque transmission device, and a final reducing device decelerating torque transmitted from the output device and outputting the decelerated torque through a differential apparatus.

Abstract: A transmission system of a hybrid electric vehicle may include a first shaft connected to an engine, a first hollow shaft disposed without rotational interference with the first shaft and provided with a first output gear, a second hollow shaft disposed without rotational interference with the first hollow shaft and provided with a second output gear, a second shaft disposed in parallel with the first shaft and operably connected to the first shaft and the first hollow shaft through a gear unit so as to selectively transmit torque of the first shaft to the first hollow shaft, a clutch selectively connecting the second shaft to the first hollow shaft, a first motor/generator operably connected to the second hollow shaft, and a second motor/generator operably connected to the second shaft.

Abstract: A power transmission system of a hybrid electric vehicle may include an input shaft receiving torque of an engine, a first planetary gear set having at least three rotation elements, a second planetary gear set having at least three rotation elements, a clutch selectively connecting two rotation elements among the at least three rotation elements of the second planetary gear set, a brake selectively connecting a rotation element of the second planetary gear set to the transmission housing, and an output gear connected to a second motor/generator and the a rotation element of the second planetary gear set.

Abstract: A transmission system of a hybrid electric vehicle may include two shafts, two hollow shafts and two motor/generators. A first shaft connected to an engine. A first hollow shaft disposed without rotational interference with the first shaft, selectively connected to the first shaft, and provided with a first output gear. A second hollow shaft disposed without rotational interference with the first hollow shaft and provided with a second output gear. A second shaft disposed in parallel with the first shaft and operably connected to the first shaft and the first hollow shaft through a gear unit to selectively transmit torque of the first shaft to the first hollow shaft. Clutches may connect the first shaft and the second shaft selectively to the first hollow shaft. A first motor/generator operably connected to the second hollow shaft and a second motor/generator operably connected to the second shaft.