| 摘要 |
PURPOSE:To prevent the line pressure from being excessively increased, by compensating the gear ratio until the time of clutch lock-up if the vehicle operating condition is shifted from a start mode into a drive mode so as control the line pressure so as to decrease the same. 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 62 is provided so as to control the clutch pressure of a hydraulic clutch 74. In this arrangement, the control section 90 controls the solenoid valve 50 for the line pressure control valve so as to compensate the gear ratio until the time of clutch lock-up when the vehicle operating condition is shifted from a start mode into a drive mode, so as to decrease the line pressure, thereby it is possible to prevent the line pressure from being excessively increased so as to enhance the efficiency of speed change.
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