Steuervorrichtung für ein stufenlos regelbares Getriebe für Kraftfahrzeuge.

摘要

A continuously variable transmission (T) for a motor vehicle has a closed hydraulic circuit (5) disposed between a hydraulic pump (2) and a hydraulic motor (4) with the hydraulic motor being of the variable displacement type. The hydraulic pump (2) is driven by the engine (E) and the hydraulic motor (4) is driven by the hydraulic pressure from the hydraulic pump for driving the road wheels (W). A pair of bypass passages (6a,6b) are connected between the two oil passages (51,5h) of the closed hydraulic circuit between the hydraulic pump and hydraulic motor and a clutch valve (7a,7b) is disposed in each bypass passage for adjusting the opening of that bypass passage. The opening of the bypass passages (6a,6b) corresponding to the amount of operation of the clutch valves (7a,7b) when the transmission receives driving forces from the road wheels (W) during deceleration is controlled so as to be greater than the opening of the bypass passages when the transmission is driven by the engine (E) to drive the road wheels.