Control system for a Continuously Variable Transmission with two pairs of conical sheaves each with an adjustable running radius, the sheave of each pair being coupled to a hydraulic actuator and the inlet port of each actuator being connected with the hydraulic actuator setting means, fed from the outlet port of a hydraulic displacement pump, connected to a supply of hydraulic medium and coupled to an electric motor which is controlled by a controller which controls the speed of the electric motor with a first control signal which is generated as a function of the actual transmission ratio of the transmission on one hand and of the desired speed of change of this transmission ratio on the other hand, all this in such a way that the speed of this first motor increases with an increase of the transmission ratio of the transmission on one hand and an increase of the speed of change of the ratio on the other hand, while the outlet port of the displacement pump is connected to the inlet of an electronically controllable pressure relief valve of which the set point is determined by a second control signal as a function of the set transmission ratio on one hand and the value of the actual torque transmitted through the transmission on the other hand, in such a way that de value of the resulting hydraulic pressure increases as the transmission ratio increases on one hand, and as the torque transmitted through the transmission increases on the other hand.

A control method of a continuously variable transmission mounted on a vehicle includes performing advance compensation in a speed ratio control system of the continuously variable transmission, and making an advance amount according to a vibration frequency of torsional vibration of an input shaft of the continuously variable transmission which is the advance amount of the advance compensation variable in accordance with an operation state of the vehicle. A feedback gain of speed ratio control of the continuously variable transmission performed in the speed ratio control system is variable in accordance with an operation state of the vehicle. When the advance amount is made variable, the advance amount is made variable in accordance with the feedback gain.

A device for controlling a gear ratio of a hydrostatic mechanical power-split transmission comprises an input switch (1) which, when rotated, produces a particular transmission characteristic and, at the same time, limits the maximum pressure. The selected position of the input switch (1) selects a particular maximum pressure curve from a large number of stored maximum pressure curves.

According to the present invention, there is provided a method of reducing output torque deficits during the launch of a vehicle having a continuously variable transmission, wherein the variator has an input connected to a prime mover and an output. The method comprises the steps of determining a rate of change of ratio in the transmission, and predicting a required motor speed ratio rate of change value of the variator on the basis of: (i) the determined rate of change of ratio in the transmission, and (ii) the configuration of the transmission. The speed of the variator output is adjusted so as to achieve the required motor speed ratio rate of change value.

A control apparatus for a drive-force transmitting apparatus that includes a transmission having primary and secondary pulleys. When a detection accuracy of rotational speed of the primary and secondary pulley is not assured, the control apparatus sets each of (i) a secondary-thrust calculation thrust ratio value used for calculation of a secondary thrust that is to be applied to the secondary pulley and (ii) a primary-thrust calculation thrust ratio value used for calculation of a primary thrust that is to be applied to the primary pulley, such that each of the secondary-thrust calculation thrust ratio value and the primary-thrust calculation thrust ratio value is dependent on a result of a determination as to whether an actual gear ratio of the transmission is the highest gear ratio and a result of a determination as to whether an input torque inputted to the transmission is lower than a given torque value.

An apparatus for ratio control of a continuously variable transmission includes a driver commanded ratio unit outputting a signal defining a commanded ratio. A clamp control portion is in communication with the driver commanded ratio unit. The clamp control portion includes: a ratio limits and override ring selecting a ratio matching the commanded ratio from an executable functions having stored ratio code data; a screening monitor continuously receiving output from the executable functions and using an input from a vehicle speed signal to compute minimum and maximum ratio limits for the ratio selected by the ratio limits and override ring; and a ratio control execution ring in communication with the screening monitor. The ratio control execution ring calculates a range of pressures allowed for operation of both primary and secondary pulleys of the continuously variable transmission.

A method of controlling a continuously variable transmission includes monitoring powertrain operating conditions, and calculating, via an electronic controller, a commanded clamping force based on the powertrain operating conditions, wherein the commanded clamping force includes a commanded clamping force of an input pulley and a commanded clamping force of an output pulley on the endless rotatable device. The method also includes activating, via the electronic controller, at least one of the input actuator and the output actuator such that an axial component of the input wedge force and the axial force of the input actuator together provide the commanded clamping force of the input pulley, and an axial component of the output wedge force and the axial force of the output actuator together provide the commanded clamping force of the output pulley.

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.

In a first process, a tangential friction coefficient of a non-slippage side pulley of a drive pulley and a driven pulley is estimated from a tangential friction coefficient and a winding diameter of a slippage side pulley. In a second process, torque transmitted by a metal belt is calculated from the tangential friction coefficient and the winding diameter. In a third process, a required axial thrust of the non-slippage side pulley is calculated from the torque and the winding diameter. In a fourth process, the gear ratio is changed by reducing a ratio holding axial thrust of the non-slippage side pulley toward the required axial thrust. Therefore, the gear shifting can be performed merely by reducing the axial thrust of the non-slippage side pulley, and thus it is possible to improve the durability of the pulleys or the metal belt and to reduce a load of a hydraulic pump.

In a control device of a vehicle power transmission device, a first meshing clutch has a drive power source side meshing member coupled to a power transmission member, an auxiliary drive wheel side meshing member coupled to the power transmission member, and an actuator engaging or releasing the drive power source side meshing member and the auxiliary drive wheel side meshing member, and when a rotation speed difference between a rotation speed of the drive power source side meshing member and a rotation speed of the auxiliary drive wheel side meshing member is larger than a predefined value at the time when a first meshing clutch is brought into an engaged state, a clamping pressure on a transmission belt is increased as compared to when a rotation speed difference is equal to or less than a predefined value.