XXX

(XX Institute of Automotive Electrical Appliances)

Abstract: In the engine control system, the ignition control of the engine electronic control ignition device includes ignition advance angle control, electrifying time control and knocking.

Control three aspects. Their control principles, control modes, control methods and control circuits are introduced respectively.

In the centralized electronic control system of the engine, ECU (Electronic Control)

Device) is an electronic integrated control device. It is not only used to control combustion.

At the same time, the fuel injection system also has ignition control, idle speed control and exhaust.

Emission control, air intake control, supercharging control, self-diagnosis and fault protection.

And other control functions. In which the ignition control is burdensome.

One of the main functions. In the engine control system, the electronic ignition device

(Electronic Ignition Advance, ESA for short)

Ignition control includes ignition advance angle control, power-on time control and explosion.

Three aspects of earthquake control.

1 development of engine ignition control system

In the traditional carburetor gasoline engine, the ignition control system is composed of

Through the traditional (contact) to non-contact development process. exist

In this process, the distributor in the system still adopts mechanical separation.

Center and vacuum advance mechanism to control the ignition advance angle of the engine.

The fuel injection control system has undergone mechanical control (K system),

Electromechanical hybrid control (K-E system) to electronic control (EFI

System) process. With the appearance and development of EFI system, ignition

The control system adopts electronic control ignition device.

With the development of electronic industry, the ignition control of EFI system has also been improved.

It has gone through the process from ordinary (traditional) type to electronic control type. In k system or

In the EFI system equipped with ordinary distributor, because the mechanical type is still used

Centrifuge and vacuum propulsion mechanism cannot affect the working state of the engine.

Based on multivariable and nonlinear control of various factors, this EFI system

Known as the common EFI system. Electronic ignition device (ESA) is adopted.

In the EFI system, mechanical centrifugation and distributor vacuum are eliminated.

The propulsion mechanism even removes the distributor, and its function is completely performed by ESA.

Bear, it can make the engine in the best condition under any circumstances.

Ignition advance state, realizing three functions: ignition advance angle

Control, electrifying time control and knocking control.

2 ESA ignition advance angle control

In the ECU, the memory of the engine under various working conditions is pre-stored.

And the optimal ignition advance angle under different operating conditions. Engine running

ECU determines the basis according to the engine speed and load signal.

The ignition advance angle is corrected according to other related signals, and most

Then determine the ignition advance angle and output the ignition finger to the ignition electronic assembly.

Signals to control the ignition system.

2 1 optimal ignition advance angle

Usually take the point where the engine emits the maximum power and the fuel consumption is the minimum.

The ignition advance angle is called the optimal ignition advance angle. For modern cars,

The best ignition advance angle should not only ensure the power and combustion of the engine

Fuel economy has reached the best, and emission pollution must be minimized.

2.2 Factors affecting ignition advance angle

2.2. 1 engine speed When the engine speed rises, ignition starts.

The lead angle increases accordingly (but the relationship is nonlinear), and it is ordinary.

The EFI system adopts mechanical centrifugal adjustment in advance.

Therefore, the adjustment curve is quite different from the ideal ignition adjustment curve.

When ESA is used, the actual ignition angle of the engine can be advanced.

Close to the ideal ignition advance angle.

2.2.2 Absolute pressure (load) of intake manifold when the intake manifold

When the pressure is high (low vacuum and heavy load), the ignition advance angle is required.

Small; When the intake manifold pressure is low (high vacuum and low load),

The ignition advance angle is required to be large. But they are also nonlinear. Permanent

In the EFI system, mechanical vacuum is used to adjust in advance.

Economizer, so the adjustment curve is very different from the ideal ignition adjustment curve.

It's huge. When ESA is used, the actual ignition of the engine can be improved.

The inclination angle is close to the ideal ignition advance angle.

2.2.3 Octane number of gasoline Engine Under certain conditions,

There is a knocking phenomenon. Knocking will reduce engine power and increase fuel consumption.

Engine overheating is very harmful to the engine. Engine explosion

Impact is closely related to the quality of gasoline, and octane number is often used to represent gasoline.

Explosion-proof performance The higher the octane number of gasoline, the better the antiknock performance.

The ignition advance angle can be increased; The lower the octane number, the worse the antiknock performance and ignition performance.

The lead angle should be reduced. In the ordinary ignition system without electronic control, it is

It is achieved by manually adjusting the initial position of the distributor. exist

In EFI, in order to meet the demand of gasoline with different octane numbers,

Two ignition timing diagrams are stored in ECU, which can be used in practice.

Choose according to different gasoline varieties. In the factory, it's usually open.

The switch is set at the position of unleaded premium gasoline.

2.2.4 Other factors The optimal ignition advance angle is also related to engine combustion.

The shape of the combustion chamber, the temperature, air-fuel ratio, atmospheric pressure,

Cooling water temperature and other factors. In the common EFI system, when

When the above factors change, the system cannot adjust the ignition advance angle.

When using ESA, the engine will work under various working conditions and operating conditions.

Can provide an ideal ignition advance angle, so the power of the engine

Sex, economy and emissions can all be optimized.

2.3 Composition and function of ignition advance angle control system (Table 1)

Table 1 Composition and Function of Ignition Advance Angle Control System

Nominal utility

sensor

Air flowmeter (for L EFI)

The intake manifold absolute pressure sensor (used for DEEFI) detects the intake air quantity.

The distributor crankshaft position sensor (NE signal) detects the crankshaft angle (speed). The camshaft position sensor (G 1, G2 signal) detects the angular reference position of the camshaft (crankshaft).

The throttle position sensor inputs a signal for correcting the ignition advance angle to the ECU.

The water temperature sensor detects the temperature of engine cooling water and inputs the signal to correct the ignition advance angle to ECU.

Start switch (start signal) inputs the signal that the engine is starting to ECU.

The air conditioner switch A/C inputs the working state (on and off) signal of the air conditioner to ECU.

The vehicle speed sensor detects the vehicle speed and inputs the vehicle speed signal to the ECU.

The neutral start switch detects that the shift lever is in the N position or the P position.

The knock sensor detects the engine knock signal.

The ignition electronic assembly (ignition module) controls the primary current of the ignition coil according to the ignition control signal output by ECU.

On and off, generating secondary high voltage. Meanwhile, the ignition confirmation signal is fed back to ECU.

The ECU calculates the optimal ignition advance angle according to the signal input by each sensor, and

Transmit the ignition control signal to the ignition electronic assembly.

2.4 control mode of ignition advance angle

2.4. 1 ignition timing control

In ESA, the control of ignition advance angle includes engine starting.

Two basic situations during and after startup.

A. ignition time control during starting (fig. 1a)

When the machine is started, the speed is low (usually 500 rpm).

), because the intake manifold pressure signal or intake signal is unstable,

Therefore, the ignition time is usually fixed at the initial ignition advance angle (its size

Depending on the engine). At this time, the ignition time has nothing to do with the engine working condition,

Therefore, solids are directly controlled by sensor signals without ECU calculation.

Fixed initial ignition advance angle. When the engine speed exceeds a certain value

It is automatically switched to be controlled by the ignition timing signal IGT of ECU.

B ignition time control after starting (fig. 1b), according to relevant

Based on the signal from the sensor, ECU calculates the optimal ignition time,

The ignition timing signal IGT is output to control the ignition of the ignition electronic component.

At this time, the ignition time is determined by the intake manifold pressure signal (or intake air signal).

Numbers) and engine speed to determine the basic ignition advance angle and correction.

Decide. The calibration items vary from engine to engine and from engine to engine.

Figure 1 Ignition Time Control

(a) Ignition time control during starting (b) Ignition time control after starting

Modified characteristic curve.

The above two situations can be summarized as follows: