Chery A15. Manual — part 250

- Basic fuel injection time
The basic fuel injection time provides the relationship between engine displacement and spray
nozzle throughput.
- Storage battery voltage correction
When the storage battery voltage changes, the voltage correction will guarantee the correct fuel
quantity injected.

6. Ignition control function
The MT20-based system features closed-loop computerized control, sequential multi-injection,
grouped direct ignition and three-way catalyst post treatment.
Closed-loop control is adopted for the engine fuel supply and idle speed control which features
the ability to accommodate any difference of the system and its relevant mechanical parts arising
out of manufacturing and wearing so that the integrity of the car is achieved.
The system divides the engine’s four cylinders into the two groups of 1-4 and 2-3 for
independent ignition control; grouped control optimizes and simplifies the structure so that the
component costs and manufacturing and processing costs can be reduced.
The system uses three-way catalyst to conduct post treatment to the engine exhaust and turn it
into harmless gas before it is emitted into the air.
Three-dimensional figure for engine ignition

As actane rating is low, the ignition advance
angle shall be reduced to avoid explosion.

At the same engine speed, the higher the engine load
is, the

lower the ignition advance angle will be

.

The higher the engine speed is, the farther the piston
will move in the same period, the higher the air
mixture pressure and temperature will be, the quicker
the combustion will be and the higher the ignition
advance angle will be.

Three-dimensional Figure for Engine Ignition Timing

0

-30

-60

-90

-

120

30

60

90

120

150

180

210

240

270

300

330

360

390

420

450

480

510

540

570

600

630

660

690

1缸

曲轴转角

58X

曲轴信号

1-4 缸线圈

A

线圈驱动

2-3 缸线圈

B

线圈驱动

1 缸工况

3 缸工况

4 缸工况

1 缸进气门开启

1X

凸轮信号

压缩行程

进气行程

排气行程

作功行程

压缩行程

进气行程

排气行程

作功行程

压缩行程

进气行程

排气行程

作功行程

压缩行程

进气行程

排气行程

作功行程

压缩行程

进气行程

排气行程

作功行程

2 缸工况

1 缸喷嘴

A

喷嘴驱动

4 缸喷嘴

C

喷嘴驱动

3 缸喷嘴

B

喷嘴驱动

2 缸喷嘴

D

喷嘴驱动

20

15

10

5

25

30

35

40

45

50

55

5

10

15

20

25

30

35

40

45

50

55

5

10

15

58X

齿 数

补偿喷油脉冲

正常喷油脉冲

MT20

/

点顺序喷射分组点火发

动机管理系

统

控制时序图

多

Control Timing Figure for MT20 Sequential Multi-injection

Grouped Ignition Engine Management System

1 缸工况：Cylinder 1 working condition
3 缸工况：Cylinder 3 working condition
4 缸工况：Cylinder 4 working condition
2 缸工况：Cylinder 2 working condition
压缩行程：Compression stroke
进气行程：Intake stroke
排气行程：Exhaust stroke
作功行程：Power stroke
1 缸进气门开启：Air intake valve of cylinder 1 open

1 缸喷嘴喷嘴驱动 A：Cylinder 1 nozzle drive A
3 缸喷嘴喷嘴驱动 B：Cylinder 3 nozzle drive B
4 缸喷嘴喷嘴驱动 C：Cylinder 4 nozzle drive C
2 缸喷嘴喷嘴驱动 D：Cylinder 2 nozzle drive D
正常喷油脉冲：Normal fuel spraying pulse
补偿喷油脉冲：Compensational fuel spraying pulse
1-4 缸线圈线圈驱动 A：Cylinder 1-4 coil drive A
2-3 缸线圈线圈驱动 B：Cylinder 2-3 coil drive B
1 缸曲轴转角：Cylinder 1 crank shaft turning angle
齿数：Number of teeth
曲轴信号：Crank shaft signal
凸轮信号：Cam signal
Coil magnetization control
The time for ignition coil magnetization determines the ignition energy of the spark plug. Too
long a magnetization time will damage the coil or coil drive while too short a magnetization time
will result in combustion.
Startup mode
Under the startup mode, the system uses a fixed ignition angle to ensure that the air mixtures in
the cylinder will be ignited. When the engine speed goes up, the ignition angle will exit the
startup mode.


7. Calculation of ignition advance angle

主 点 火 角

气 温 修 正

怠 速 修 正

空 调 修 正

水 温 修 正

减 速 断 油

修 正

海 拔 修 正

点 火 提 前 角 计 算

点 火 提 前 角

动 力 加 浓

修 正

加 速 修 正

Calculation of ignition advance angle（从主点火角开始顺时针翻译）
Main ignition angle

Deceleration fuel cutoff correction Higher ARF correction

Air conditioner correction

Acceleration correction

Ignition advance angle

Idle speed correction Altitude correction Ambient temperature correction
Water temperature correction
- Main ignition advance angle

After the engine water temperature becomes normal, the main ignition angle when the throttle
opens is usually the minimum ignition angle or knock critical point (KBL) at the maximum
brake torque; the ignition angle when the throttle closes shall be smaller than the MBT point to
acquire stable idle speed.
On the prerequisite that the cool driving performance is not affected, the basic angle may not be
MBT or KBL ignition angle during heating of the catalyst and shall be delayed for as long as
possible in order to ignite the catalyst as soon as possible.
- Ignition advance angle correction
Water temperature correction, air intake temperature correction, altitude compensation correction,
idle speed correction, acceleration correction, higher ARF correction, deceleration fuel cutoff
correction, air conditioner control correction, waste emission recycling correction
- Acceleration correction
Ignition advance angle deceleration correction is used to reduce the engine speed fluctuation
caused by transmission system vibration and eliminate the knock caused during acceleration,
thus smoothing the acceleration.
- Higher ARF correction
The ARF will be increased to the LBT in order to obtain better power and torque. Therefore, the
ignition advance angle may be corrected to obtain the MBT point.
-Deceleration fuel cutoff correction
When the deceleration fuel cutoff mode is exited, the ignition angle may be corrected to make it
smooth for the throttle to close.
- Air conditioner control correction
When the air conditioner is turned off at engine idle speed, the ignition advance angle may be
corrected to make it smooth for the engine speed to change.
- Three-dimensional figure for ignition correction

Air filling efficacy@TPS/RPM

Air

filling efficacy with throttle

opened@MAP/RPM

Correction coefficient for air
filling temperature

Optimal ignition advance
angle

Higher ARF

Air filling efficacy with throttle
closed@MAP/RPM