| 摘要 |
PURPOSE:To reduce a speed change shock by shifting a sub-speed changer when speed change permission judged from a speed change chart and speed change permission judged based on the actual speed change ratio of a stepless speed changer are obtained in a system serially connecting the stepless speed changer and the sub-speed changer. CONSTITUTION:In a system transmitting the engine power to a drive shaft 20 via a fluid coupling 10, a belt type stepless speed changer 12, a sub-speed changer 14 having at least two forward gear stages, an intermediate gear device 16 and a differential device 18, when the sub-speed changer 14 is to be shifted from the high-speed gear stage to the low-speed gear stage, first the actual vehicle speed and speed change ratio are calculated. Next, a shift down is judged from a pre-stored speed change chart based on the actual vehicle speed and throttle valve opening, and whether the actual speed change ratio is within a shift down permission region or not is judged. If shift down permission is judged in both cases, the sub-speed changer 14 is shifted from the high-speed gear stage to the low-speed gear stage. |
