Electrohydraulic controller of vehicular continuously variable automatic transmission - exercises electronic control of prim. and sec. pulley-positioning pressures with facility for emergency manual override

摘要

The transmission ratio of the belt drive (16) between sliding pulleys (14,15) from a combustion engine (2) varies with load and speed in response to operations of a hydraulic transmission valve (4) and a pressure valve (5). The transmission valve control pressure (P5) in normal operation is set by the electronic controller (6) of a magnetic valve (61), and in emergency by a manual valve (7) giving a predetermined ratio which is suitable both for guaranteed starting and for driving at reduced speed. ADVANTAGE - No additional hydraulic control valves are required for emergency operation, and electronic complexity is reduced.