A method is disclosed for controlling a drill-free curve-CVT including a ring wheel, a set of planet wheels, and a sun wheel, wherein the ring and sun wheel are clamped together. The normal forces between the ring and sun wheel on the one hand and the planet wheels on the other hand are well defined when the transmission ratio is constant. The normal forces for constant ratio are called the static values. The method is configured so that during a continuous increase or decrease of the transmission ratio, any force component added to the static values of the first and/or the second normal force is either zero or smaller than a predefined force component to maintain a microslip condition of the rolling contacts between the planet wheels and the ring and sun wheels. This control of the forces is applied regardless of the speed of the ratio change.

Provided herein is a control system for a multiple-mode continuously variable transmission having a ball planetary variator. The control system has a transmission control module configured to receive a plurality of electric input signals, and to determine a mode of operation from plurality of control ranges based at least in part on the plurality of electronic input signals. The system also has an adaptive ratio control module configured to store at least one calibration map, and configured to determine an adaptive speed ratio command signal during operation of the CVP.

Provided herein is a control system for a multiple-mode continuously variable transmission having a ball planetary variator. The control system has a transmission control module configured to receive a plurality of electronic input signals, and to determine a mode of operation from a plurality of control ranges based at least in part on the plurality of electronic input signals. The system also has an adaptive ratio control module configured to store at least one calibration map, and configured to determine an adaptive speed ratio command signal during operation of the CVP.

A continuous variable planetary (CVP) system includes a CVP hub, which includes a shift mechanism including a shift driver element, and a processing server system to calibrate the CVP system and detect errors within the CVP system. The processing server system performs continuously monitoring or obtaining a transmission speed ratio of the CVP hub. Upon detecting that the transmission speed ratio reaches a particular value, the processing server system records a corresponding position of the shift driver. The processing server system calibrates the CVP system based on the particular value, the corresponding position, and a known relationship between transmission speed ratios and positions of the shift mechanism. The processing server system determines or verifies a full underdrive (FUD) position by iteratively reducing a transmission speed ratio from the particular value until an onset of a backlash condition is detected and determines or verifies a full overdrive (FOD) position.

A controller of a toroidal continuously variable transmission comprises a position control unit which outputs a driving signal to a hydraulic actuator to control a roller position. The hydraulic actuator includes a biasing mechanism which forcibly keeps the roller position at a predetermined position in a case where the driving signal meets a predetermined condition. The position control unit is configured to perform a start-up control during start-up of the toroidal continuously variable transmission. During the start-up control, the position control unit is configured to output the driving signal to reciprocate a spool of the hydraulic actuator in a case where a temperature of hydraulic oil supplied to the hydraulic actuator is lower than a reference temperature, and output the driving signal which meets the predetermined condition in a case where the temperature of the hydraulic oil has become equal to or higher than the reference temperature thereafter.

A method is disclosed for controlling a drill-free curve-CVT including a ring wheel, a set of planet wheels, and a sun wheel, wherein the ring and sun wheel are clamped together. The normal forces between the ring and sun wheel on the one hand and the planet wheels on the other hand are well defined when the transmission ratio is constant. The normal forces for constant ratio are called the static values. The method is configured so that during a continuous increase or decrease of the transmission ratio, any force component added to the static values of the first and/or the second normal force is either zero or smaller than a predefined force component to maintain a microslip condition of the rolling contacts between the planet wheels and the ring and sun wheels. This control of the forces is applied regardless of the speed of the ratio change.

A continuous variable planetary (CVP) system includes a CVP hub, which includes a shift mechanism including a shift driver element, and a processing server system to calibrate the CVP system and detect errors within the CVP system. The processing server system performs continuously monitoring or obtaining a transmission speed ratio of the CVP hub. Upon detecting that the transmission speed ratio reaches a particular value, the processing server system records a corresponding position of the shift driver. The processing server system calibrates the CVP system based on the particular value, the corresponding position, and a known relationship between transmission speed ratios and positions of the shift mechanism. The processing server system determines or verifies a full underdrive (FUD) position by iteratively reducing a transmission speed ratio from the particular value until an onset of a backlash condition is detected and determines or verifies a full overdrive (FOD) position.

A continuous variable planetary (CVP) system includes a CVP hub, which includes a shift mechanism including a shift driver element, and a processing server system to calibrate the CVP system and detect errors within the CVP system. The processing server system performs continuously monitoring or obtaining a transmission speed ratio of the CVP hub. Upon detecting that the transmission speed ratio reaches a particular value, the processing server system records a corresponding position of the shift driver. The processing server system calibrates the CVP system based on the particular value, the corresponding position, and a known relationship between transmission speed ratios and positions of the shift mechanism. The processing server system determines or verifies a full underdrive (FUD) position by iteratively reducing a transmission speed ratio from the particular value until an onset of a backlash condition is detected and determines or verifies a full overdrive (FOD) position.

Inventive embodiments are directed to components, subassemblies, systems, and/or methods for continuously variable accessory drives (CVAD). In one embodiment, a skew-based control system is adapted to facilitate a change in the ratio of a CVAD. In another embodiment, a skew-based control system includes a skew actuator coupled to a carrier member. In some embodiments, the skew actuator is configured to rotate a carrier member of a CVT. Various inventive traction planet assemblies can be used to facilitate shifting the ratio of a CVT. In some embodiments, the traction planet assemblies include legs configured to cooperate with the carrier members. In some embodiments, a traction planet assembly is operably coupled to the carrier members. Embodiments of a shift cam and traction sun are adapted to cooperate with other components of the CVT to support operation and/or functionality of the CVT. Among other things, shift control interfaces for a CVT are disclosed.

A controller of a toroidal continuously variable transmission comprises a position control unit which outputs a driving signal to a hydraulic actuator to control a roller position. The hydraulic actuator includes a biasing mechanism which forcibly keeps the roller position at a predetermined position in a case where the driving signal meets a predetermined condition. The position control unit is configured to perform a start-up control during start-up of the toroidal continuously variable transmission. During the start-up control, the position control unit is configured to output the driving signal to reciprocate a spool of the hydraulic actuator in a case where a temperature of hydraulic oil supplied to the hydraulic actuator is lower than a reference temperature, and output the driving signal which meets the predetermined condition in a case where the temperature of the hydraulic oil has become equal to or higher than the reference temperature thereafter.