1991-11-01

Application of Electrohydraulic Control Valves to Automatic Transmissions - - An Approach to Improving Shift Quality 912487

The hydromechanical control systems conventionally used in passenger car automatic transmissions have been replaced in recent years with electrohydraulic control systems in order to improve shift quality and expand the range of control freedom. The electrohydraulic control valves employed in automatic transmissions today are generally built with either PWM control switching valves or proportional control valves. The major performance requirements that these electrohydraulic actuators must satisfy include good hydraulic response, hydraulic stability and suppression of surge pressure. This paper presents different examples of specific problems that have been encountered when these two types of electrohydraulic actuators have been applied to transmission control systems. Several measures for improving the performance of electrohydraulic actuators are then described based on simulation results and experimental validation. Finally, the results of an experiment conducted with a control system built with an improved electrohydraulic actuator are presented to show the high level of advanced shift control that was obtained.

SAE MOBILUS

Subscribers can view annotate, and download all of SAE's content. Learn More »

Access SAE MOBILUS »

Members save up to 18% off list price.
Login to see discount.
Special Offer: Download multiple Technical Papers each year? TechSelect is a cost-effective subscription option to select and download 12-100 full-text Technical Papers per year. Find more information here.
We also recommend:
TECHNICAL PAPER

Assessment of Operation Speed and Precision of Electropneumatic Actuator of Mechanical Transmission Clutch Control System

2018-01-1295

View Details

TECHNICAL PAPER

Improving Automatic Transmission Shift Quality by Feedback Control with a Turbine Speed Sensor

911938

View Details

TECHNICAL PAPER

Electronic Controls for Bus, Truck and Off–Highway Vehicle Transmissions

820909

View Details

X