Vehicle power transmission device

摘要

A power transmission apparatus for a vehicle is provided which is equipped with a power split device and a speed variator. The power transmission device is designed to set a speed ratio of speed of rotation of an output of a power source to speed of rotation of a driven wheel in a power circulation mode of a power split device to lie within one of a positive range in which a sign of the speed ratio is positive and a negative range in which a sign of the speed ratio is negative. This results in a decrease in degree of torque acting on the speed variator such as a continuously variable transmission, thus permitting a required degree of durability of the speed variator to be reduced.

主权项

1. A power transmission apparatus for a vehicle comprising:
a power split device which includes a first, a second, and a third rotor which rotate in conjunction with each other to split power among the first, second, and third rotors, the third rotor being coupled mechanically to a driven wheel of a vehicle; and a speed variator joined mechanically to the power split device, wherein the power split device is placed in a power transmission mode in which power, as produced by a power source, is transmitted to the third rotor through the second rotor and then to the driven wheel as torque, wherein in the power transmission mode, the power split device is also placed in a power circulation mode wherein the power is circulated between the first and second rotors, and wherein a speed ratio of a speed of rotation of an output of the power source to a speed of rotation of the driven wheel in the power circulation mode is set to lie within one of a positive range in which a sign of the speed ratio is positive or a negative range in which a sign of the speed ratio is negative.