Doosan DP158L Series, Руководство по эксплуатации и техническому обслуживанию

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Control Unit (1)
The engine speed control unit used by Doosan is an electronic control unit designed to be able to respond
quickly and accurately to changes in the instantaneous load.
This control unit is designed to receive a signal from the magnetic pick-up sensor (speed sensor) of the
engine when a fluctuation occurs in the engine load and then be automatically fine-tuned to the changes in the
engine rpm, thereby providing high reliability and satisfying adverse environmental engine conditions.
The main feature of this device is that it includes functions for adjusting the amount of starting fuel and the
fluctuations in the speed. It thereby helps to reduce engine emissions. It also has a function for parallel engine
operation, a protective function for when the battery polarity is reversed, and functions designed to ensure
safety during short circuits in the actuator circuit, battery power cut-off or failure of the magnetic pick-up sen-
sor.
Description of Functions
In order for the controller or actuator to function normally, the output signal value of the magnetic pick-up sen-
sor must be 0.5 ~ 120V, and this signal is connected to "C" and "D" on the controller. Terminal "D" is con-
nected to the negative ("-") battery terminal "E" inside the controller terminal.
When the signal from the magnetic pick-up sensor reaches the controller, it is converted into an analog speed
signal and amplified.
In the event that the controller fails to receive the output value from the magnetic pick-up sensor during oper-
ation, the controller’s output circuit shuts off all current flowing to the actuator.
The controller’s integrated circuit receives the signal from the magnetic pick-up sensor based on the set
speed value. This range is 8 : 1 and can be adjusted with the 25-turn potentiometer. This speed setting output
value becomes the input value traveling to the dynamic control section. With the help of this dynamic control
circuit, most of the engine and fuel systems perform evenly and stably.
CAUTION
For the connection to the magnetic pick-up sensor, either two wires twisted together or
shielded wire should be used, but be careful that this shield is not grounded to the engine.
If grounded to the engine, an incorrect speed signal may be delivered to the speed controller.
The controller’s circuit may be affected by adjustments to the gain and stability. In order to increase the oper-
ating responsiveness of the actuator within the governor, turn the gain clockwise to adjust it. The adjustment
range for the gain is approximately 33 : 1.
If the stability is turned in the clockwise direction, the actuator, i.e. governor reaction time increases.
While the engine is running, the starting fuel in the controller can be adjusted from an almost closed state to a
completely open state. When the engine is started, the adjusted position of the speed is determined initially by
the set idle value and the speed ramping circuit. When the engine has finished speeding up, the engine is
kept at the set speed while satisfying the speed fluctuation rate of the controller.
The controller’s output circuit switches the current for activating the actuator at a frequency of around 500 Hz.
This is because no visible changes appear in the output curve for the actuator since the switching frequency is
much higher than the natural frequency of the actuator.
The transistors in the output section are switched in order to achieve effective control of the output, thereby
reducing power consumption within the controller. The output circuit delivers up to 10 A of continuous current
from the 12V or 24V battery system at 25.
The actuator responds to the average value of the current based on the position of the fuel control lever.