Work vehicle and control method for same

摘要

A target-input-torque determination unit determines the target input torque on the basis of the transmission required horsepower. The target input torque is a target value for the torque to be inputted to a power-transmission device. A target-output-torque determination unit determines the target output torque, which is a target value for the torque to be outputted by the power-transmission device. A command-torque determination unit uses torque-balance information to determine command torque for the motor from the target input torque and the target output torque. The target-input-torque determination unit determines the upper limit of the target input torque on the basis of an upper-limit-target-input-torque line and the engine rotation speed. The upper-limit-target-input-torque line sets a value smaller than the target output torque of the engine determined using the engine required horsepower and the engine rotation speed for the upper-limit value of the target input torque.

主权项

1. A work vehicle, comprising:
an engine; a hydraulic pump driven by the engine; a work implement driven by hydraulic fluid discharged from the hydraulic pump; a work implement operating member for operating the work implement; a travel device driven by the engine; a power-transmission device configured to transmit driving power from the engine to the travel device; a vehicle speed detecting unit for detecting a vehicle speed; an accelerator operating member; an accelerator operation detecting unit for detecting an operation amount of the accelerator operating member; and a control unit configured to control the power-transmission device; the power-transmission device including
an input shaft;an output shaft;a gear mechanism including a planetary gear mechanism, the gear mechanism being configured to transmit rotation of the input shaft to the output shaft; anda motor connected to a rotating element of the planetary gear mechanism; andthe power-transmission device configured so that a rotation speed ratio of the output shaft with respect to the input shaft is changed by changing the rotation speed of the motor, and the control unit including
a transmission requirement determination unit for determining a transmission required horsepower on the basis of the vehicle speed and the operation amount of the accelerator operating member;a work implement requirement determination unit for determining a work implement required horsepower on the basis of the operation amount of the work implement operating member;an engine requirement determination unit for determining an engine required horsepower on the basis of the work implement required horsepower and the transmission required horsepower;a target-input-torque determination unit that determines a target input torque which is a torque target value inputted to the power-transmission device, on the basis of the transmission required horsepower;a target-output-torque determination unit that determines a target output torque which is a torque target value outputted from the power-transmission device;a storage unit for storing torque-balance information for defining a relationship between the target input torque and the target output torque so that a balance of the torques in the power-transmission device is achieved; anda command-torque determination unit that uses the torque-balance information to determine a command torque for the motor from the target input torque and the target output torque; the target-input-torque determination unit determining an upper limit of the target input torque from an upper limit target input torque line and the engine rotation speed; and the upper limit target input torque line defining a value smaller than the target output torque of the engine determined from the engine required horsepower and the engine rotation speed, as the upper limit of the target input torque.