Digital Algorithm for Hydraulic Actuator

An electronically controlled Easy Drive System (EDS), the NAVI-5, is now used in the Isuzu Aska, to permit automatic gear changes with in the basic structure of a manual transmission. This is achieved by synchromeshed transmission gears and a single disk dry clutch operated by hydraulic actuators and controlled by a microcomputer which is based on a unique digital algorithm. However this technical feasibility for use in the field has hitherto been considered difficult. At the same time, excellent engine power and fuel economy equal to that attainable with the conventional manual transmission have been achieved using this system which makes maximum use of the advantage of its manual transmission construction.

This paper describes an actuator for the clutch, which makes complex clutch operation possible and has the following features:

1. (1)
   High speed solenoid valves, which are simply constructed and highly durable.
2. (2)
   A closed loop control which feeds back clutch stroke.
3. (3)
   A pulse width modulating (PWM) control suitable for a microcomputer.