| 摘要 |
PURPOSE:To miniaturize an automatic transmission by constituting a gear train so as to set a specified shift step with a combined pattern of plural sorts of engagement and release of a friction engaging means. CONSTITUTION:A control unit consisting of a hydraulic controller C and an electronic control unit E sets a shift step on the basis of running conditions, but as to the shift step where there are plural sorts of engagement and release patterns, it selects such a pattern that engages a friction engaging means (second clutch means K2) equipped with an accumulator 7 and executes a speed change, if possible. To be concrete, the first gear speed is set in advance after engaging clutches K1, K4, and K5 and a brake B1, by way of example, and when shift to the second gear speed is judged, the clutch k2 is engaged but the clutch K4 is disengaged. At this time, timing for engagement is optimized by the accumulator 7. Likewise, even when shifting from the third gear speed to the fourth one, the clutch K2 is operated. Therefore the number of accumulators becomes lessened. |
