Patent ID: 6292731
Filing Date: 2001-09-18
Classification: F16H

Abstract:
A transmission control system for a multiple ratio automatic transmission, said transmission comprising a first multiple ratio planetary gear set and a second simple planetary gear set arranged in series between an engine and a driven member, and an electronic transmission controller;multiple clutches and brakes for controlling relative motion of gear elements of said first and second gear sets to establish five forward driving speed ratios;a source of line pressure;a valve circuit establishing fluid pressure distribution from said pressure source to said clutches and brakes including at least two variable force solenoid valves and at least three on/off shift solenoid valves;brake servo control valve means in said circuit for controlling pressure distribution to said brakes and a clutch control valve means in said circuit for controlling pressure distribution to said clutches;one of said variable force solenoid valves establishing controlled pressure distribution to the clutches and brakes for said multiple ratio planetary gear set through said brake servo control valve means and through said clutch control valve means;another of said variable force solenoid valves establishing controlled pressure distribution to the clutches and brakes for said simple planetary gear set through said brake servo control valve means and through said clutch control valve means;said shift solenoid valves communicating hydraulically with said brake servo control valve means and said clutch control valve means for effecting shifting movement thereof to establish and disestablish pressure distribution paths to said clutches and brakes whereby speed ratio change patterns are obtained;a manual select system in said circuit between said electronic transmission controller and said clutch and brake servo control valve means having an automatic mode ratio change position for automatic ratio changes and multiple manual mode positions for effecting continuous manually selected ratios;said controller having output driver portions communicating with said variable force solenoid valves and said shift solenoid valves and signal input portions receiving engine, transmission and manual select system operating variables whereby shift solenoid valve states are determined by said variables and by selected positions of said manual select system.