Transmission device for work vehicles

摘要

Disclosed is a transmission device for work vehicles, said transmission device being capable of being used with high-horsepower engines, without an accompanying loss of power transmission efficiency or fuel economy. The transmission device is provided with: an input shaft that transmits power from an engine; a continuously-variable transmission that is disposed on the input shaft and outputs power transmitted from the input shaft, steplessly converting the speed thereof; and a reversing clutch device that outputs, either in a forward rotational direction or a reverse rotational direction, power outputted from the continuously-variable transmission. The reversing clutch device can be selectively switched, and the gear ratio can be steplessly changed by the continuously-variable transmission.

主权项

1. A transmission system comprising:
a continuously variable transmission including an input part, an output part and a speed control device for setting a speed ratio of the output part to the input part in a range between a minimum speed ratio and a maximum speed ratio; an output member; a reverse drive train, a first forward speed drive train, and a second forward speed drive train arranged in parallel to one another; a reverse clutch for drivingly connecting the output member to the output part of the continuously variable transmission via the reverse drive train; a first forward clutch for drivingly connecting the output member to the output part of the continuously variable transmission via the first forward speed drive train; a second forward clutch for drivingly connecting the output member to the output part of the continuously variable transmission via the second forward speed drive train; and a planetary gear mechanism, wherein when the second forward clutch is engaged, the planetary gear mechanism combines a rotary power inputted from the input part of the continuously variable transmission with a rotary power inputted from the output part of the continuously variable transmission via the second forward speed drive train, and outputs a resultant force to the output member, wherein one of the reverse clutch, the first forward clutch, and the second forward clutch is selectively engaged to drivingly connect the output member to the output part of the continuously variable transmission via one selected among the reverse drive train, the first forward speed drive train and the second forward speed drive train, wherein in a first range where the reverse drive train is selected to drivingly connect the output member to the output part of the continuously variable transmission by selectively engaging the reverse clutch, increase of speed of the output member rotating in a reverse direction from minimum to maximum corresponds to increase of the speed ratio set by the speed control device of the continuously variable transmission from the minimum speed ratio to the maximum speed ratio, wherein in a second range where the first forward speed drive train is selected to drivingly connect the output member to the output part of the continuously variable transmission by selectively engaging the first forward clutch, increase of speed of the output member rotating in a normal direction from minimum to maximum corresponds to increase of the speed ratio set by the speed control device of the continuously variable transmission from the minimum speed ratio to the maximum speed ratio, and wherein in a third range where the second forward speed drive train is selected to drivingly connect the output member to the output part of the continuously variable transmission by selectively engaging the second forward clutch, increase of speed of the output member rotating in the normal direction from minimum to maximum corresponds to reduction of the speed ratio set by the speed control device of the continuously variable transmission from the maximum speed ratio to the minimum speed ratio, wherein the speed ratio of the continuously variable transmission reaches the minimum speed ratio at a transition between the first range and the second range, and the speed ratio of the continuously variable transmission reaches the maximum speed ratio at a transition between the second range and the third range.