Work vehicle and work vehicle control method

A work vehicle comprising:

• an engine;
• a work implement pump driven by the engine;
• a work implement driven by hydraulic fluid discharged from the work implement pump;
• a travelling apparatus driven by the engine;
• a power transmission device including an input shaft for inputting driving power from the engine, an output shaft for outputting driving power transmitted to the travelling apparatus, and a motor;
• a vehicle speed detecting unit configured to detect a vehicle speed;
• a work implement pump pressure detecting unit configured to detect a work implement pump pressure of the work implement pump;
• a work implement operating member for operating the work implement;
• a work implement operation detecting unit configured to detect an operation amount of the work implement operating member;
• an accelerator operating member;
• an accelerator operation detecting unit configured to detect an operation amount of the accelerator operating member;
• and
• a control unit configured to control the power transmission device;
• the power transmission device being 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;
• the control unit including
• a work implement requirement determination unit configured to determine a work implement required power on the basis of an operation amount of the work implement operating member and the work implement pump pressure;
• a transmission requirement determination unit configured to determine a transmission required power on the basis of the vehicle speed and the operation amount of the accelerator operating member;
• and
• a distribution ratio determination unit configured to determine a transmission output ratio that is a value derived by dividing the driving power actually supplied from the engine to the power transmission device by the transmission required power, and a work implement output ratio that is a value derived by dividing the driving power actually supplied from the engine to the work implement pump by the work implement required power,
• in a first case
• in which the engine rotates at a rotation speed equal to or greater than a first rotation speed that is the rotation speed of the engine at a maximum matching point where an upper limit target input torque line and an engine torque line intersect and
• in which the sum of the work implement required power and the transmission required power is greater than a first distributable power that a predetermined preferential distribution power subtracted from a load upper limit power of the engine at the first rotation speed leaves,
• the distribution ratio determination unit is configured to allocate the smaller of a transmission compensation power and the transmission required power to the power transmission device and distribute the remainder of the first distributable power to the work implement pump and to the power transmission device, thereby determining a first work implement allocation power allocated to the work implement pump and a first transmission allocation power allocated to the power transmission device.