Patent ID: 6364801
Filing Date: 2002-04-02
Classification: F16H,Y10T

Abstract:
A control system for an automatic transmission comprising a power transmission mechanism incorporating a plurality of power transmission paths, a plurality of hydraulically operated frictionally engaging means provided inside said power transmission mechanism for selecting said power transmission paths individually, a plurality of shift control valves for controlling supply of hydraulic oil to said hydraulically operated frictionally engaging means, a forward/reverse hydraulic servomechanism for switching and selecting either said power transmission paths assigned for a forward drive range or said power transmission paths assigned for a reverse drive range, a D inhibitor valve which is switched for controlling supply of line pressure to forward drive and reverse drive servo-oil chambers of said forward/reverse hydraulic servomechanism, and a plurality of solenoid valves for controlling actuation of said shift control valves and said D inhibitor valve; wherein:said D inhibitor valve is switchable between a forward drive position which connects said reverse drive servo-oil chamber to a drain and a reverse drive position which allows said line pressure into said reverse drive servo-oil chamber; said control system comprising, as neutral modes to be set when a manipulation is made to shift said transmission into a neutral range: a first neutral mode in which said D inhibitor valve is switched to said forward drive position and said forward drive servo-oil chamber is connected to said drain through any of said shift control valves; and a second neutral mode in which said D inhibitor valve is switched to said reverse drive position and said forward drive and reverse drive servo-oil chambers are connected to said drain through any of said shift control valves.