The electronically controlled engine should not only accomplish the tasks that the carburetor has to accomplish, but also accomplish the tasks that the carburetor is difficult to accomplish. For example, the air-fuel ratio concentration of combustible mixture can be controlled within the required range. The oil circuit and circuit of carburetor engine are clearly divided and do not affect each other. The fuel supply system of the electronically controlled engine is added with an electronic control part, which makes the oil circuit and the circuit connected with each other, which not only affects the work of the engine fuel system, but also affects the normal work of the engine. Due to the increase of electronic control devices in electronically controlled engines, the overall structure of the engine (including the electronic control system) is more complicated.
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Structural composition
principle of operation
Parameters to be measured
superiority
basic thought
In the early stage, electronic technology replaced mechanical control technology to realize the function of the system and expand its function, which greatly improved the performance; After the development of electronic technology to a certain extent, the system principle can be fundamentally changed, thus breaking through the limitations and greatly improving the engine performance.
Electronically controlled engine
Structural composition
Electronic control unit
Electronic control unit (ECU) is the core of engine electronic control system. It completes the collection of various engine parameters, the control of injection quantity and injection timing, and determines the function of the whole electronic control system.
sensor
The sensor transmits the information of engine working condition and environment to ECU instantly and truly through various signals.
In other words, all ECU knows is an engine composed of many signals. Therefore, the accuracy, reproducibility and immediacy of sensor information directly determine the quality of control.
actuating mechanism
Various control functions performed by the electronic control system are realized by various actuators.
In the control process, the actuator converts the control signal from ECU into some mechanical or electrical motion, which causes the change of engine operating parameters and completes the control function.
principle of operation
Taking the engine speed and load as the basic signals reflecting the actual working conditions of the engine, the basic fuel injection quantity and timing are determined by referring to the fuel injection quantity and timing diagrams corresponding to various working conditions of the engine obtained by experiments, and then various compensations are made according to various factors (such as water temperature, oil temperature, atmospheric pressure, etc.). ) to obtain the optimal fuel injection quantity and fuel injection timing or ignition timing, and then the actuator controls the output.