Drive to neutral shift control system

摘要

A control system for an automatic transmission, which receives the rotation of the engine through a fluid coupling, and which has a clutch applied when a forward running range is selected and released when a neutral range is selected and a range selecting mechanism for selecting a range. The control system includes a range detector for detecting the selected range, a hydraulic circuit and a control unit. The hydraulic circuit includes a hydraulic servo which is fed an oil pressure for applying the clutch and a manual valve movable between at least a forward range position for generating a forward range oil pressure and a neutral range position, by operation of the range selecting mechanism. A regulator valve regulates the forward range oil pressure to generate a regulated oil pressure. A solenoid valve is turned ON/OFF by the control unit to generate a signal oil pressure for switching a change-over valve between a first position feeding the forward range oil pressure to the hydraulic servo and a second position feeding the regulated oil pressure to the hydraulic servo. The control unit delays output of the signal solenoid valve, if a switching from the forward running range to the neutral range is detected by the range detector, so that the change-over valve remains in the second position until lapse of a set time period, and is then moved to a first position after the set time period has elapsed.