A working vehicle of this invention includes a main speed change structure that includes a continuously variable speed change structure such as an HMT structure and a multi-speed speed change structure capable of switching between a first power transmission state with a first gear ratio and a second power transmission state with a second gear ratio providing a higher speed than the first gear ratio. A control device causes the continuously variable speed change structure to be accelerated to a forward travel side in accordance with an accelerating operation of a speed change operation member in a forward travel direction, and causes the multi-speed speed change structure to be changed from a first power transmission state to a second power transmission state when the rotational speed of the speed change output shaft reaches a switching speed set to exceed a work speed range.

A work machine includes an engine, a transmission connected to the engine to change a transmission gear ratio continuously, a travel device connected to the transmission to cause the work machine to travel, a sensor arranged and configured to detect an acceleration of the work machine, and a controller. The controller selectively execute a first mode and a second mode that limits a target tractive force of the machine in comparison to the first mode. The controller weakens limitation of the target tractive force and determines the target tractive force when the acceleration of the machine in the second mode is less than a predetermined acceleration threshold. The controller determines a target transmission gear ratio in accordance with the target tractive force. The controller controls the transmission based on the target transmission gear ratio.

A work machine includes an engine, a transmission connected to the engine to change a transmission gear ratio continuously, a travel device connected to the transmission to cause the work machine to travel, a sensor arranged and configured to detect an acceleration of the work machine, and a controller. The controller selectively execute a first mode and a second mode that limits a target tractive force of the machine in comparison to the first mode. The controller weakens limitation of the target tractive force and determines the target tractive force when the acceleration of the machine in the second mode is less than a predetermined acceleration threshold. The controller determines a target transmission gear ratio in accordance with the target tractive force. The controller controls the transmission based on the target transmission gear ratio.

A nonlinear closed-loop control combined with an integral time-delay feedback control is disclosed to adjust a speed ratio of an infinitely variable transmission (IVT) system. A speed ratio control for an IVT system involves a forward speed controller and a crank length controller for different speed ranges. The time-delay control is designed to reduce speed fluctuations of the output speed of an IVT with an accurate speed ratio. The speed ratio of an IVT with the disclosed control strategy can achieve an excellent tracking response for the desired constant output speed and reduce speed fluctuations of the output speed of an IVT by the time-delay feedback control.

Methods and systems are provided for improving torque control of a vehicle that includes simulated shifting of a step gear ratio transmission. In one example, a propulsive effort request is gradually incrementally increased or decreased to provide a smooth torque transition, thereby providing a smoother vehicle speed change and improve vehicle drivability.

A continuously variable transmission has a variator (4) structured to be able to continuously vary a transmission ratio and a control unit (100). The control unit (100) continuously varies a transmission ratio of the variator (4) in a continuously variable shift mode. In a manual mode in which a manual mode switch (36c) is ON, the transmission ratio is maintained. When a shift switch (36a, 36b) is operated by a driver during the manual mode, the control unit (100) performs shift of the variator (4) so as to change an input rotation speed of the variator (4) by a predetermined rotation speed (ΔN1) regardless of a vehicle speed.

A continuously variable transmission has a variator (4) structured to be able to continuously vary a transmission ratio and a control unit (100). The control unit (100) continuously varies a transmission ratio of the variator (4) in a continuously variable shift mode. In a manual mode in which a manual mode switch (36c) is ON, the transmission ratio is maintained. When a shift switch (36a, 36b) is operated by a driver during the manual mode, the control unit (100) performs shift of the variator (4) so as to change an input rotation speed of the variator (4) by a predetermined rotation speed (ΔN1) regardless of a vehicle speed.

A device for a vehicle including a power transfer device, the power transfer device having an input pulley, an output pulley, and an endless rotary member, the device including: a memory configured to store mapping data that include data that prescribe mapping that represents correspondence between an input variable and an output variable, the data being learned through machine learning, the input variable being at least one of input rotational speed-related data, and output rotational speed-related data, the output variable specifying whether an abnormality is caused in the endless rotary member; and a processor configured to acquire the input variable, acquire the output variable corresponding to the input variable using the mapping data, and determine, based on the output variable, whether an abnormality is caused in the endless rotary member.

A device for a vehicle including a power transfer device, the power transfer device having an input pulley, an output pulley, and an endless rotary member, the device including: a memory configured to store mapping data that include data that prescribe mapping that represents correspondence between an input variable and an output variable, the data being learned through machine learning, the input variable being at least one of input rotational speed-related data, and output rotational speed-related data, the output variable specifying whether an abnormality is caused in the endless rotary member; and a processor configured to acquire the input variable, acquire the output variable corresponding to the input variable using the mapping data, and determine, based on the output variable, whether an abnormality is caused in the endless rotary member.

A vehicle includes an engine, a continuously variable transmission, and a controller. The controller, responsive to a request to manually shift the continuously variable transmission and the engine being on, operates the continuously variable transmission atone of a predetermined number of discrete ratios such that a speed of the engine changes by at least a predetermined amount.