Method of controlling line pressure in continuously variable transmission

Abstract

Abstract PURPOSE:To make it possible to eliminate a shift in line pressure due to variations, by calculating a compensating value in accordance with a hydraulic pressure and a throttle opening degree in a predetermined operating condition, and by compensating and controlling a desire line pressure in accordance with the compensating value when the control mode is shifted into an open loop control mode. CONSTITUTION:A belt drive type continuously variable transmission 2 is composed of a primary pressure control valve 34 as a speed change control valve, a constant pressure control valve 38, a line pressure control valve 44 and a clutch pressure control valve 52 in a hydraulic circuit, and the valves 34, 44, 52 are controlled by a control section 70 through solenoid valves 42, 50, 58 respectively. The clutch pressure control valve 52 is provided so as to control the clutch pressure of a hydraulic start clutch 62. In this arrangement, the control section 70 calculates a compensating value in accordance with an actual hydraulic pressure detected by a pressure sensor 68 and a throttle opening degree when the line pressure becomes equal to the clutch pressure after the control mode is shifted from a start mode into a drive mode, and the desired line pressure is compensated and controlled in accordance with the compensating value during open-loop control operation.

Inventors

• 👤 Yoshinobu Yamashita
• 👤 Sadayuki Hirano
• 👤 Katsuaki Murano
• 👤 Takumi Tatsumi
• 👤 Hiroaki Yamamoto

Bibliographic Details