The present invention provides a hybrid powertrain comprising an internal combustion engine (ICE), a transmission (2), a first electric motor (4a) and a second electric motor (4b), wherein the transmission comprises an input shaft (1) to which the ICE is connected via a main clutch (3), an output shaft (6) and a gear assembly providing at least two different gear ratios that may be selected for transfer of mechanical power from the input shaft (1) to the output shaft (6), the first electric motor (4a) is connected to the input shaft (1) via a first gear (i.sub.x), such that torque and rotation may be transferred between the first electric motor and the input shaft, and the second electric motor (4b) is connected to the input shaft (1) via a first clutch (5a) and the first gear (i.sub.x), such that torque and rotation may be transferred between the second electric motor (4b) and the input shaft (1), and connected to the output shaft (6) via a second clutch (5b) and a second gear (i.sub.y), such that torque and rotation may be transferred between the second electric motor (4b) and the output shaft (6), wherein the first electric motor (4a) is connected to the second electric motor (4b) via the first clutch (5a), and the first electric motor (4a), the second electric motor (4b), the first clutch (5a) and the second clutch (5b) form parts of a torque transfer path bypassing the at least two different gear ratios, the torque transfer path arranged to transfer torque from the input shaft (1) to the output shaft (6) during a gearshift.

A power transmission apparatus of a hybrid vehicle having an engine and first and second motor-generators includes: a planetary gear set disposed on a first motor shaft of the first motor-generator, and including a planet carrier connected to an engine shaft, a sun gear connected to the first motor shaft, and a ring gear connected to a drive gear through a one-way clutch, a second motor shaft gear connected to a second motor shaft of the second motor-generator, an output shaft disposed between the engine shaft and the second motor shaft, and a brake unit to selectively connect the sun gear and the ring gear to a transmission housing. In particular, the output shaft is externally gear-meshed with the drive gear and the second motor shaft gear respectively through a driven gear, and externally gear-meshed with a final reduction gear of the differential gear through an output gear.

A power transmission apparatus of a hybrid vehicle including an engine and a first motor-generator and a second motor-generator includes a compound planetary gear set engaged to a first motor shaft of the first motor-generator, and configured to receive an engine torque from the engine through a one-way clutch, to receive a motor torque of the first motor-generator, and to output an output torque as a combination of the engine torque and the motor torque through a drive gear, a motor shaft gear connected to a second motor shaft of the second motor-generator, and an output shaft disposed between an engine torque shaft connected to the engine and the second motor shaft connected to the second motor, and gear-engaged with the drive gear and the motor shaft gear respectively through a driven gear, and a brake unit configured to selectively connect one of a first sun gear and a second sun gear of the compound planetary gear set to a transmission housing to act as a fixed element.

A control system for a hybrid vehicle that can reduce a power loss resulting from shifting an operating mode from motor mode to hybrid mode is provided. A transmission that is adapted to distribute torque applied to an input element to a reaction element and an output element, and to change a ratio between a first torque delivered to the reaction element and a second torque delivered to the output element. A controller is configured to start an engine in a high mode in which a torque ratio of the output element to the input element is small if the vehicle speed is higher than a threshold value, and to start the engine in a low mode in which the torque ratio is greater if the vehicle speed is lower than the threshold value.

A drive system includes a first planetary gear set selectively coupled to a first electromagnetic device, a second planetary gear set coupled to a second electromagnetic device and directly coupled to the first planetary gear set, an engine directly coupled to the first planetary gear set with a connecting shaft, and an output shaft coupled to the first planetary gear set. The first and second electromagnetic devices include a first shaft and a second shaft, respectively. The connecting shaft extends through the second electromagnetic device and through the second planetary gear set to the first planetary gear set. The first shaft, the second shaft, the first planetary gear set, the second planetary gear set, the connecting shaft, and the output shaft are radially aligned, forming a straight-thru transmission arrangement.

A hybrid powertrain apparatus for a vehicle, includes first and second input shafts concentrically provided to selectively receive power of an engine, a planetary gear set including a first rotation element, a second rotation element, and a third rotation element, wherein the first rotation element is connected to the first input shaft and the second rotation element is connected to a first motor, a clutch device configured to fix the remaining rotation element of the planetary gear set or connect the remaining rotation element to the second input shaft, a second motor connected to the second input shaft, and an output gear provided on the second input shaft.

A power transmission apparatus of a hybrid vehicle including an engine and a first motor-generator and a second motor-generator includes a compound planetary gear set engaged to a first motor shaft of the first motor-generator, and configured to receive an engine torque from the engine through a one-way clutch, to receive a motor torque of the first motor-generator, and to output an output torque as a combination of the engine torque and the motor torque through a drive gear, a motor shaft gear fixedly connected to a second motor shaft of the second motor-generator, and an output shaft disposed in parallel to and between an engine torque shaft connected to the engine and the second motor shaft connected to the second motor, and gear-meshed with the drive gear and the motor shaft gear respectively through a driven gear.

A drive system includes a first planetary gear set coupled to a first electromagnetic device, a second planetary gear set coupled to a second electromagnetic device and directly coupled to the first planetary gear set, an engine directly coupled to the first planetary gear set with a connecting shaft, and an output shaft coupled to the first planetary gear set. The first and second electromagnetic devices include a first shaft and a second shaft, respectively. The connecting shaft extends through the second electromagnetic device and through the second planetary gear set to the first planetary gear set. The first shaft, the second shaft, the first planetary gear set, the second planetary gear set, the connecting shaft, and the output shaft are radially aligned, forming a straight-thru transmission arrangement.

A drive system includes: a first planetary gear unit, in which a carrier is connected to an internal combustion engine, a sun gear is connected to a first MG, and a ring gear is connected, via a first drive gear and a first driven gear, to a counter shaft; and a second planetary gear unit, in which a brake is provided to a sun gear, a carrier is connected to the internal combustion engine, and a ring gear is connected, via a second drive gear and a second driven gear, to the counter shaft. A gear ratio of the first drive gear and the first driven gear is larger than a gear ratio of the second drive gear and the second driven gear.

A control unit embedded in a work vehicle includes a clutch controlling unit and a motor controlling unit. The clutch controlling unit is configured to disengage a first clutch in a condition that the first clutch is engaged and a second clutch is disengaged, when a first moving direction inputted through a forward/rearward movement switch operating device as an instruction of the operator and a second moving direction determined based on a vehicle speed detected by a vehicle speed detecting unit are different from each other, and in addition, when and the vehicle speed falls in a preliminarily set first range. The motor controlling unit is configured to control a motor to reduce a relative rotational speed of the second clutch after the first clutch is disengaged.