A control method for a power transmission device includes: determining whether a difference between an actual speed ratio of a variator and a speed ratio at which a movable pulley contacts a stopper is equal to or less than a predetermined value; and performing a switching of a switching valve when being determined that the difference is equal to or less than the predetermined value.

A method is provided for estimating input torque and output torque in a continuously variable transmission having a variator. The method comprising the steps of determining (202) a transmission input and/or output speed, calculating (204) the speed of each of a plurality of transmission components by reflecting the transmission input and/or output speed through the transmission to each of the plurality of transmission components, and calculating (208) the speed rate of change of each of the plurality of transmission components. The inertia torque of each of the plurality of transmission components is calculated (210) based upon its respective speed rate of change and a predetermined component inertia value (209). The method further comprises the steps of determining (211) a motor torque of the variator, and calculating (212) a transmission input torque and transmission output torque by reflecting the motor torque of the variator through the transmission to the transmission input and output. The calculated transmission input and output torque values are adjusted (214) to account for the calculated inertia torque values of those of the plurality of transmission components which lie between the variator and the transmission input, and the variator and the transmission output, respectively.

The control mode is switched between a first control mode configured to control the speed change pump based on an actual speed ratio being an actual speed ratio of the variator, and a second control mode configured to control the speed change pump based on an actual working pressure being an actual working pressure of the variator. In the first control mode, the actual speed ratio is calculated based on a detected value of a vehicle speed; and the speed change pump is controlled to cause the actual speed ratio to approach the target speed ratio. In the second control mode, the actual working pressure is detected and the speed change pump is controlled to cause the actual working pressure to approach a target working pressure corresponding to the target speed ratio. In a situation or a condition where the detection accuracy of the vehicle speed by the vehicle speed sensor decreases, the control mode is switched from the first control mode to the second control mode.

A method and system for selecting a speed ratio for a continuously variable transmission (CVT) of a vehicle during braking. The method and system includes determining a Current Actual Speed Ratio of the CVT when the distance of a brake pedal travel exceeds a predetermined distance, determining, by a transmission control module (TCM), an amount of Available Speed Ratio Change (r), a Current Ratio Change Capability (Current-{dot over (r)}), and a Predictive Ratio Change Capability (Predictive-{dot over (r)}). The method further includes the TCM calculating a Time to Reach the Minimum Under-drive Ratio (t.sub.UD), calculating a Predicted Velocity of the Vehicle (v.sub.Pr) using (t.sub.UD), determining a Desired Speed Ratio of the CVT using the Predicted Velocity of the Vehicle (v.sub.Pr), and actuating the CVT to the Desired Speed Ratio.

A control apparatus for a vehicle driving apparatus includes: a first-operating-state determining portion configured to determine whether the driving apparatus is in a first operating state, by determining (i) whether a first drive-force transmitting path is established to cause a drive force to be transmitted through a gear mechanism and (ii) whether there is a probability of generation of noises between an input shaft and an continuously-variable transmission; and a belt-clamping-force controlling portion configured to control a belt clamping force of the continuously-variable transmission, when it is determined that the driving apparatus is in the first operating state, to start execution of a belt-clamping-force increasing control for increasing the belt clamping force such that the belt clamping force is made larger when the driving apparatus is in the first operating state than when the driving apparatus is in an operating state that is different from the first operating state.

A control system for a vehicle uses one or more inputs of a velocity request, a brake request, a speed request, travel direction indication, engine speed, and vehicle speed to determine a control strategy for a continuously variable transmission. A target engine speed is selected based upon the inputs, and the engine and continuously variable transmission ratio are controlled to achieve the target engine speed while controlling the vehicle according to the inputs. In some embodiments, the control strategy further selects the target engine speed according to accessory system demands, such as a hoist or lift system.

A control device for a continuously variable transmission includes a belt type continuously variable transmission and a controller. The controller is configured to calculate an actual gear shift ratio based on rotation speed sensor values from a primary rotation speed sensor and a secondary rotation speed sensor, and to perform gear shift ratio control using feedback control to converge the actual gear shift ratio to a target gear shift ratio. The controller is further configured to stop calculation of the actual gear shift ratio when one of the rotation speed sensor values is less than a first threshold value determined based on a lower limit value of sensor detection accuracy, and stop calculation of the actual gear shift ratio even when one of the rotation speed sensor values is the first threshold value or greater, when a deceleration level of the drive wheel is a prescribed deceleration level or greater.

A controller of a power transmission system for a vehicle includes an electronic control unit. When a difference between a secondary pressure set by use of a command pressure of the electromagnetic control valve for the secondary pulley, and an actual pressure obtained by a hydraulic pressure sensor, is larger than a predetermined pressure difference, the electronic control sets a primary pressure and the secondary pressure such that a speed ratio of a continuously variable transmission becomes substantially equal to a maximum value. The electronic control unit determines that there is an abnormality that an output pressure of the electromagnetic control valve for a secondary pulley is low, when the speed ratio is smaller than a predetermined first determination value, and determines that there is an abnormality in the hydraulic pressure sensor, when the speed ratio is larger than a predetermined second determination value.

A control device for a continuously variable transmission performs feedback control so that an actual transmission control value becomes a target transmission control value. The control device includes a phase lead compensation unit configured to perform phase lead compensation of the feedback control, a phase delay compensation unit configured to perform phase delay compensation of the feedback control, a first peak value frequency determination unit configured to change a peak value frequency of the phase lead compensation according to a transmission ratio of the continuously variable transmission, and a second peak value frequency determination unit configured to change a peak value frequency of the phase delay compensation based on the peak value frequency of the lead compensation.

A method of controlling driving of a CVT vehicle during cornering performed by a controller, may include determining whether it is necessary to perform an auxiliary control process to enhance a re-acceleration response after entering the corner, by determining a travelling state of the vehicle; setting a target gear ratio instead of a gear ratio obtained based on a shift pattern when the determining produces an affirmative result indicating that it is necessary to perform the auxiliary control process; and performing gear shifting of a CVT to follow the target gear ratio set in the setting of the gear ratio.