A method of controlling a hybrid power train may include: driving a first input shaft connected to a second motor-generator by the second motor-generator to synchronize a speed of a driven gear of a target gear position with a speed of an output shaft; moving a sleeve to directly connect the second input shaft, the output shaft, and the driven gear of the target gear position; decreasing torque of the first motor-generator and increasing torque of the second motor-generator to converge torque transferred from the second motor-generator to the output shaft, to torque of the output shaft; moving the sleeve to release the second input shaft and maintain only the output shaft and the driven gear; and increasing torque of an engine and decreasing the torque of the second motor-generator to converge torque transferred from the engine to the output shaft, to the torque of the output shaft.

A method of controlling a hybrid power train may include: driving a first input shaft connected to a second motor-generator by the second motor-generator to synchronize a speed of a driven gear of a target gear position with a speed of an output shaft; moving a sleeve to directly connect the second input shaft, the output shaft, and the driven gear of the target gear position; decreasing torque of the first motor-generator and increasing torque of the second motor-generator to converge torque transferred from the second motor-generator to the output shaft, to torque of the output shaft; moving the sleeve to release the second input shaft and maintain only the output shaft and the driven gear; and increasing torque of an engine and decreasing the torque of the second motor-generator to converge torque transferred from the engine to the output shaft, to the torque of the output shaft.

A four-wheel drive vehicle comprises: main drive wheels and sub-drive wheels; a first input rotating member; a first output rotating member; a second input rotating member; a second output rotating member; a first dog clutch; a second dog clutch; a synchromesh mechanism. In the case of canceling a disconnect state in which the power transmitting member interrupts power transmission from the drive power source and the sub-drive wheels, the control device controls an engagement torque of the coupling to a preset first torque and operates the synchromesh mechanism to engage the first dog clutch when it is determined that the rotation speeds are synchronized between the second input rotating member and the second output rotating member, and controls the engagement torque of the coupling to a second torque smaller than the first torque to engage the second dog clutch when it is determined that the first dog clutch is engaged.

A four-wheel drive vehicle comprises: main drive wheels and sub-drive wheels; a first input rotating member; a first output rotating member; a second input rotating member; a second output rotating member; a first dog clutch; a second dog clutch; a synchromesh mechanism. In the case of canceling a disconnect state in which the power transmitting member interrupts power transmission from the drive power source and the sub-drive wheels, the control device controls an engagement torque of the coupling to a preset first torque and operates the synchromesh mechanism to engage the first dog clutch when it is determined that the rotation speeds are synchronized between the second input rotating member and the second output rotating member, and controls the engagement torque of the coupling to a second torque smaller than the first torque to engage the second dog clutch when it is determined that the first dog clutch is engaged.

A method for power transmission method includes providing first and second shafts, first and second gear assemblies between the first and second shafts, and first and second coupling assemblies. The first coupling assembly coupling the first shaft to the first gear assembly, and the second coupling assembly coupling the first shaft to the second gear assembly. The speed of the first shaft varies, wherein the deployment of a locking element of the second coupling assembly is based on the speed of the first shaft.

A method for power transmission method includes providing first and second shafts, first and second gear assemblies between the first and second shafts, and first and second coupling assemblies. The first coupling assembly coupling the first shaft to the first gear assembly, and the second coupling assembly coupling the first shaft to the second gear assembly. The speed of the first shaft varies, wherein the deployment of a locking element of the second coupling assembly is based on the speed of the first shaft.

A synchromesh mechanism is activated when cancelling a disconnection state, and, when an electronic control unit determines that a rotation speed of an input shaft has been synchronized with a rotation speed of a first ring gear, a second intermeshing clutch is engaged, and then a first intermeshing clutch is engaged. For this reason, in the first intermeshing clutch, a decrease in the rotation speed of the first ring gear is suppressed as a result of engagement of the second intermeshing clutch. This suppresses out of synchronization between the rotation speed of the first ring gear and the rotation speed of the input shaft at the time when the first intermeshing clutch is engaged.

A method for power transmission method includes providing first and second shafts, a gear assembly having first and second gear ratios, and first and second coupling assemblies. The first coupling assembly enabling torque transfer from the first shaft to the second shaft, and the second coupling assembly enabling torque transfer from the first shaft to the second shaft. The speed of the first shaft varies, wherein the deployment of a locking element of the second coupling assembly is based on the speed of the first shaft.