| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent the racing of an engine and ensure improved shift quality at an upshift operation in a extremely low engine-load range with an upshift controller which positions gears into the upshift state by depressurizing the first coupling element having been coupled and pressurizing the second coupling element having been decoupled. SOLUTION: An automatic-transmission upshift controller is provided with an accumulator back-pressure control valve (f) for receiving a pressure corresponding to the engine load and a pressure with which a second coupling element (b) is supplied as operation signal pressures to thereby switch the supply over to the drain of the back pressure of an accumulator (c) when the differential pressure between both pressures becomes a preset differential pressure, and an accumulator back-pressure control means (i) for pressurizing the accumulator back-pressure control valve (f) to apply pressure to a second coupling element (b) or outputting to a valve control actuator (g) a command to prevent a timing valve (h) to be switched to the drain side from being switched over to the drain side, when the engine load detected by an engine-load detection means (g) is found in an extremely low range in the determination of an upshift.</p> |
