A continuously variable transmission includes a primary pulley, a secondary pulley, a metal belt and a controller. The metal ring includes a ring and a plurality of elements bundled by the ring. The elements have respective receiving portions opening in a radial direction of the metal belt and receive the ring in the receiving portions. Assuming a direction perpendicular to a circumferential direction and a radial direction of the metal belt as a lateral direction L, the controller executes a falling-off countermeasure control of the element when a relative movement of the element in the lateral direction L with respect to the ring is detected or a presence of an action of a force on the element which causes such relative movement is detected.

Methods and systems for a hydromechanical transmission are provided herein. In one example, a vehicle system is provided that includes a hydromechanical transmission with a power-take off (PTO) that is designed to rotationally couple to an implement. The vehicle system further includes an engine coupled to the hydromechanical transmission and a power-management control unit configured to, during a drive or coast condition, cause the power-management control unit to: determine a net available power for the hydromechanical transmission and manage a power flow between the hydromechanical transmission, a drive axle, and the implement based on the net available power.

A method and system for controlling clutch friction elements of an automatic transmission is provided. The method includes retrieving information about shift clutches from a data storage unit and acquiring information required to predict a temperature of a friction element for each shift clutch, deriving a predicted temperature value of a friction element for each shift clutch by using the information about the shift clutches and the information required to predict the temperature of the friction element, predicting whether or not overheating occurs for each shift clutch by comparing the derived predicted temperature value of the friction element for each shift clutch with an allowable temperature set for each shift clutch, and determining a target shift stage while avoiding the overheating clutch with a predicted temperature value exceeding the allowable temperature, through switching to an avoidance shift mode.

A monitoring method and device for determination of a gear-stick position, a vehicle control unit, and a vehicle. The monitoring method for determination of a gear-stick position includes: acquiring a first actual gear-stick position and a first acceptable gear-stick position calculated by a functional layer; calculating a second actual gear-stick position according to a gear-stick position signal; determining whether the first actual gear-stick position and the second actual gear-stick position are consistent; in case that the first actual gear-stick position and the second actual gear-stick position are consistent, determining whether the first acceptable gear-stick position is valid; and in case that the first actual gear-stick position and the second actual gear-stick position are inconsistent or the first acceptable gear-stick position is invalid, controlling the vehicle to enter a safe state. The present application can ensure safe driving of a vehicle.

The transmission control unit includes a gear ratio abnormality determination unit and a limp home control unit. The gear ratio abnormality determination unit is configured to determine that a gear ratio is abnormal when, during travelling at a predetermined gear position, a difference between an actual gear ratio, which is calculated based on a transmission input shaft rotation speed and a transmission output shaft rotation speed, and a set gear ratio at the predetermined gear position is equal to or greater than a set value. The limp home control unit is configured to, when the gear ratio abnormality determination unit determines that the gear ratio is abnormal, output a disengagement instruction for disengaging all of the plurality of friction elements, when it is confirmed that a neutral state is shifted to according to the output of the disengagement instruction, determine engagement/disengagement of a specific friction element among the plurality of friction elements based on rotation/stop information of a rotation member of the stepped transmission mechanism, and determine an evacuation gear position based on determination information on the engagement/disengagement of the specific friction element, and shift the gear position to the determined evacuation gear position.

A diagnosis device determines diagnoses one of primary and secondary board temperature sensors as abnormal, in response to a condition that a state in which a primary temperature sensor value and a secondary temperature sensor value deviate from each other by a predetermined value or more continues for a predetermined duration or more; performs torque limitation to limit a torque inputted from an engine to an automatic transmission, during driving in a predetermined travel section based on a predetermined condition, after the one of the primary and secondary board temperature sensors is diagnosed as abnormal; and performs transmission shift restriction to restrict shifting of the automatic transmission along with the torque limitation, in response to a condition that the one of the primary and secondary board temperature sensors continues to be diagnosed as still abnormal after the driving in the predetermined travel section is completed.

A continuously variable transmission includes a primary pulley, a secondary pulley, a metal belt wound around the primary pulley and the secondary pulley, and a controller. The metal belt includes a ring and a plurality of elements. The elements have respective receiving portions opening in a radial direction of the belt and receive the ring in the receiving portions. The controller executes a preliminary determined falling-off countermeasure control of the element when the end play larger than the predetermined length is detected to be generated or the continuously variable transmission is detected to be under the operation condition in which the end plays concentrate.

An automatic transmission where the control portion controls the adjustment solenoid valve so that the circulation hydraulic pressure equals to a second circulation hydraulic pressure higher than the first circulation hydraulic pressure when the rotational speed difference between the output rotational speed of the fluid transmission device and the rotational speed of the driving source is more than the predetermined rotational speed.

An abnormality determination device for a continuously variable transmission is provided in which since the abnormality determination device which calculates a compression stiffness of a metal belt from an amplitude ratio between a variable component of the rotational speed of an input shaft and a variable component of the rotational speed of an output shaft, a phase lag that is an indicator of the difference in phase between a variable component of the rotational speed of the input shaft and a variable component of the rotational speed of the output shaft, and a belt pitch radius of a drive pulley or a driven pulley, and determines whether a metal ring has broken by comparing the compression stiffness of the metal belt with a preset reference compression stiffness.

Under an abnormal determination, when a transmission gear stage is switched, a torque limit value is changed from a value before switching of the transmission gear stage to a value after switching thereof in a period in which this transmission gear stage is switched.