Pressure staging in a continuously variable transmission

摘要

A vehicle includes an engine, a continuously variable transmission (CVT), and a controller. The CVT has an output shaft, a primary pulley connected to and driven by the engine, a secondary pulley connected to the output shaft, and a belt. The pulleys each have mating halves with conical faces defining a gap in which the belt is positioned. Actuators act on one of the halves of the primary and secondary pulleys in response to a respective primary and secondary pressure. The controller detects a desired CVT ratio change in response to control inputs and determines a required shift force for achieving the desired ratio change. The controller also determines whether a calibrated rate of change is achievable. The controller adjusts the primary and/or secondary pressures when the calibrated rate is not achievable, including transmitting a pressure command to at least one of the primary and secondary actuators.

主权项

1. A vehicle comprising:
a torque generating device having an output shaft; a continuously variable transmission (CVT) having an output shaft, a primary pulley connected to and driven by the output shaft of the torque generating device, a secondary pulley connected to the output shaft of the CVT, and a belt, wherein the primary and secondary pulleys each have mating halves with conical faces defining a variable-width gap therebetween in which the belt is positioned; a first actuator acting on one of the halves of the primary pulley in response to a primary pressure; a second actuator acting on one of the halves of the secondary pulley in response to a secondary pressure; and a controller in communication with the first and second actuators, wherein the controller is programmed to:
detect a desired ratio change of the CVT in response to a set of control inputs;calculate a required shift force for the desired ratio change;determine if the desired ratio change is achievable at a calibrated desired rate based on the calculated required shift force; andadjust at least one of the primary and secondary pressures ahead of an execution of the desired ratio change when the calibrated desired rate is not achievable, including transmitting a pressure command to at least one of the first and second actuators.