Continuously variable transmission and a hydraulic control method thereof

摘要

A transmission controller determines whether a shift is a kickdown, and when the shift is determined as the kickdown, the target line pressure is increased to a first target pressure corresponding to an input torque to a continuously variable transmission increased by the kickdown; the transmission controller then determines whether the line pressure has reached the first target pressure, and if determined that the line pressure has reached the first target pressure, the target line pressure is increased to a second target pressure higher than the first target pressure.

主权项

1. A continuously variable transmission that includes a primary pulley, a secondary pulley and a power transmission member wound between the pulleys and shifts by changing a groove width of each of the pulleys by changing a primary pressure supplied to the primary pulley and a secondary pressure supplied to the secondary pulley, the continuously variable transmission comprising:
an oil pump driven by an engine; a line pressure regulator valve which is a drain regulator valve that reduces a discharge pressure of the oil pump to regulate a line pressure which is a source pressure of the primary pressure and the secondary pressure, the line pressure regulator valve including a spool on whose edges a signal pressure corresponding to a target line pressure and the line pressure are acted and which opens and closes a drain port in accordance with a stroke, and a spring that biases the spool; a kickdown determining unit adapted to determine whether a shift is a kickdown; a first pressure increasing unit adapted to increase the target line pressure to a first target pressure corresponding to an input torque to the continuously variable transmission that increases by the kickdown, when the shift is determined as the kickdown; a pressure increasing determining unit adapted to determine whether the line pressure has reached the first target pressure; and a second pressure increasing unit adapted to increase the target line pressure to a second target pressure higher than the first target pressure, when the line pressure is determined as reaching the first target pressure.