Throttle Valve (DK) Motors
The throttle valve assembly consists of the DK housing with the throttle valve plate, return spring, drive motor and feedback potentiometers. The EML IIIs throttle valve plate is driven directly by the motor shaft which allows for a precise control of the throttle plate positioning.
A dual stepper motor configuration is used to drive the throttle plate. Both stepper motors are controlled through separate final stages in the EML control module and operate on the one armature. The final stages for one stepper motor windings are controlled by one micro processor while the second motor windings are controlled by the second processor. The control of the stepper motors takes place simultaneously by each processor.
The dual feedback potentiometers signal the movement and position of the throttle plate to each processor. The two potentiometers have separate power and ground circuits to ensure the reliability of their operation.
This dual redundancy system allows the EML IIIs to continue operation, without driver inconvenience, if one stepper motor or control circuit malfunctions. If the self diagnosis of the EML IIIs detects a fault with one of the stepper motor controls, it will switch off the affected circuit and continue operation from one motor control circuit. The fault will be logged and the EML fault warning will be displayed in the cluster matrix.
If a fault occurs that cannot allow continued operation of the throttle valve, the control for that bank of cylinders will be switched off.