Geely JL481Q, Руководство пользователя

Страница: 184 / 198

E
ngine management system is normally divided into three parts, i.e. sensor, controller andactuator.
Sensor: converts physical parameters of the engine into electric signals (digital or analog), so as to monitor operating
status and environmental conditions of the engine, and transmits these signals to the controller.
Controller: receives and processes various information sent by the sensor, and analyzes information to get informed of
engine status. It utilizes preset control tactics and programs to determine how to control this engine under present condi-
tions, finally converts this decision into instruction(s) and transmits it (them) to the actuator. The Controller contains a
microprocessor and stores programs or control software pre-compiled by the designer in its memory. The controller may
be considered as the brain of control system.
Actuator: receives various instructions sent by the controller, converts electric signal into action of actuating element
(action of electric element, or certain mechanical movement) through its design. Action of these elements will change
operating condition of the device, and determine operation and output of the engine.
A great deal of information runs through the entire control system. Engine management system understands operating
condition of the engine from sensor information, uses input information and self-stored information to decide control mode
and instructions, and transmits produced instruction information to the actuator to accomplish the entire control process.
the actuator to accomplish the entire control process.
The core issue in electronic control of engine fuel system is the electronic control of fuel quantity, actually, electronic control
of excess air coefficient λ.
ECU controlsλthrough control of fuel injection amount. When engine works, ECU gets airflow information from the sensor,
and determines fuel injection amount through some calculations,thereby enables excess air coefficient of gas mixture to
reach preset value. In the whole process, control instruction issued by ECU is merely a control signal to activate fuel
injector. In this fuel injection signal, ECU controls pulse width and moment of signal.
Pulse width of fuel injection signal determines the amount of fuel injection. This pulse is a function of the following param-
eters, input and output including correction form closed loop control.
(1) Objective determined by ECU through calculation- air fuel ratio
(2) Airflow value.
(3) Other parameters concerning operating condition of the engine: e.g. information provided by throttle position sensor,
oxygen sensor, water, air, temperature sensor, Pressure temperature sensor etc.
(4) Flow characteristic of fuel injector.
Chapter 15 Engine Management System
1. Electronic control of engine fuel system
Section 1 System Profile
Ignition control of engine management system includes three aspects: ignition advance angle
control, knocking control and ignition energy control (conduction angle control).
Control of ignition advance angle is the fundamental function of ignition control. Ignition advance angle = fundamental
quantity of ignition advance angle + correction quantity.
Control of ignition advance angle is also related to operating conditions of the engine. Factors that subject to operating
conditions could be expressed by the correction factor..
II. Electronic control of engine ignition system
180