Da Nang University

University of Science and Technology

Faculty of Transportation Mechanical Engineering
~~~~~~*~~~~~~

Essay
Analysis of the Structure and Operating
Characteristics of a Stationary Propulsion System in
Practical

Lecturer : Dr. Le Minh Duc

Class : 21.18
Group : 3
Students : Nguyễn Văn Anh Tuấn
Lâm Quang Vinh
Lê Trung Tuấn
Võ Văn Tuấn

DaNang 15.5.2024
Mục lục:
I) The function, structure, and operating principle of a automotive battery.
1.1 Function
1.2 Structure
1.3.Operating principle of a automotive battery
II) Compare 3 types of ignition systems in terms of structure, operating principles and
scope of application.
2.1 Structure
2.2 Operating principles
2.3 Scope of application

I)The function, structure, and operating principle of a automotive battery.

1.1 Function
+ Starting the Engine:One of the primary functions of a car battery is to provide the initial
surge of power required to start the engine. When you turn the ignition key or press the start
button, the battery delivers a high current to the starter motor, which then cranks the engine
into action.

+ Powering Electrical Systems:Apart from starting the engine, car batteries are responsible
for powering various electrical systems in the vehicle. From the lights and horn to the
infotainment system and climate control, the battery supplies electricity to these components
even when the engine is turned off.

+ Stabilizing Voltage:Car batteries also play a crucial role in stabilizing the voltage within the
vehicle's electrical system. They act as a buffer, preventing voltage spikes and drops that could
potentially damage sensitive electronics

+ Energy Storage and Regeneration:The battery's function goes beyond starting the engine and
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powering electrical systems.

+ Engine is running:Electricity from the battery may be needed to supplement the charging
system when the vehicle's electrical load requirements exceed the charging system's ability to
produce electricity. Both the battery and the alternator supply electricity when demand is high.
1.2 Structure
An automobile battery contains a diluted sulfuric acid electrolyte, positive and negative
electrodes, in the form of several plates. Since the plates are made of lead or lead-derived
materials, this type of battery is often called a lead acid battery. A battery is separated into
several cells (usually six in the case of automobile batteries), and in each cell there are several
battery elements, all bathed in the electrolyte solution.

Picture 1: Structure of a automotive battery.

1.2.1 Case: Container which holds and protects all battery components and electrolyte,
separates cells, and provides space at the bottom for sediment (active materials washed off
plates). Translucent plastic cases allow checking electrolyte level without removing vent caps.

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 Picture 2: Case

1.2.2 Cover: Permanently sealed to the top of the case; provides outlets for terminal posts,
vent holes for venting of gases and for battery maintenance (checking electrolyte, adding
water).
1.2.3 Plates: Positive and negative plates have a grid framework of antimony and lead alloy.
Active material is pasted to the grid... brown-colored lead dioxide (Pb02) on positive plates,
gray- colored sponge lead (Pb) on negative plates. The number and size of the plates determine
current capability... batteries with large plates or many plates produce more current than
batteries with small plates or few plates.

Picture 3: Plates
1.2.4 Separators: Thin, porous insulators (woven glass or plastic envelopes) are placed
between positive and negative plates. They allow passage of electrolyte, yet prevent the plates
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from touching and shorting out.
1.2.5 Cells: An assembly of connected positive and negative plates with separators in between
is called a cell or element. When immersed in electrolyte, a cell produces about 2.1
volts(regardless of the number or size of plates). Battery cells are connected in series, so the
number of cells determines the battery voltage. A "12-volt" battery has six cells.
1.2.6 Cell connectors: Heavy, cast alloy metal straps are welded to the negative terminal of
one cell and the positive terminal of the adjoining cell until all six cells are connected in series.
1.2.7. Cell partitions: Part of the case, the partitions separate each cell.
1.2.8. Terminal posts: Positive and negative posts (terminals) on the case top have thick,
heavy cables connected to them. These cables connect the battery to the vehicle's electrical
system (positive) and to ground (negative).
1.2.9. Vent caps: Types include individual filler plugs, strip-type, or box-type. They allow
controlled release of hydrogen gas during charging (vehicle operation). Removed, they permit
checking electrolyte and, if necessary, adding water.

Picture 4: Vent caps

1.2.10: Electrolyte: A mixture of sulfuric acid(H2SO4) and water (H2O). It reacts chemically
with the active materials in the plates to create an electrical pressure (voltage). And, it
conducts the electrical current produced by that pressure from plate to plate. A fully charged
battery will have about 36% acid and 64% water.
1.3 Operating principle of a automotive battery
When discharged, the battery will provide an electric current to the consumer. When the
acid in the electrolytic solution reacts with lead, it turns into water, causing electrical energy
to be released. At that time, sulfuric acid along with the negative and positive plates is
converted into lead sulfate. The discharge process causes the amount of water to increase
but reduces the amount of sulfuric acid, causing the electrolyte concentration to decrease
and the plates gradually
approach the outside due to the nature of PbSO4, causing the potential difference between
them to gradually decrease.
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When charging, the electrolyte concentration increases, the electrolyte changes into sulfuric
acid. Along with that, the positive plates will turn into lead oxide, and the negative plates
will turn into lead. At this time, the direction of the charging current is opposite to the
discharge current.

Picture 5: Operating principle of a car battery

II) Compare 3 types of ignition systems in terms of structure, operating principles and
scope of application.
+Ignition systems are divided into three basic categories:
- Distributor.
- Distributorless Ignition System (DLI) Electronic Ignition.
- Direct Ignition System (DIS).

2.1 Structure
+ Distributor
Distributor: Contains a rotor and a cap with contacts for each cylinder.
Ignition Coil: Generates high voltage needed for the spark.
Spark Plugs: Ignite the air-fuel mixture.
Points and Condenser: Used in older systems to control the coil's primary circuit.
+Distributorless Ignition System (DLI) Electronic Ignition
Ignition Coils: One coil per pair of cylinders (waste spark system) or per cylinder (coil-on-
plug system).
Electronic Control Unit (ECU): Controls timing and firing sequence.
Crankshaft Position Sensor: Provides timing information to the ECU.
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Spark Plugs: Directly connected to coils.
+ Direct Ignition System (DIS).
Coil-on-Plug (COP) Setup: Each cylinder has its own ignition coil mounted directly on top of
the spark plug.
Electronic Control Unit (ECU): Controls the ignition timing and sequence.
Crankshaft and Camshaft Position Sensors: Provide precise engine position data to the ECU.
Spark Plugs: Positioned directly under the coils.
2.2 Operating principles
+ Distributor
A distributor-based automotive ignition system connects to the camshaft with gears. In the
mechanical distributor, the gears spin the main distributor shaft. Inside, a set of “ignition
points” rubs against a multi-sided cam on the distributor shaft. The cam opens and closes the
points; they act like a mechanical switch that interrupts the current flow. That is what starts
and stops the flow of power to the ignition coil. Once the coil generates firing voltage, it
travels to the top of the coil and into the top of the distributor cap. A rotating disc attached to
the distributor shaft “distributes” the power to each of the spark plug wires.
+ Distributorless Ignition System (DLI) Electronic Ignition
This system determines spark timing based on two shaft position sensors and a computer. The
Crankshaft Position Sensor (CKP) is mounted at the front of the crankshaft or near the
flywheel on some vehicles, and the Camshaft Position Sensor (CMP) is mounted near the end
of the camshaft. These sensors continually monitor both shafts’ positions and feed that
information into a computer.
+ Direct Ignition System (DIS).
Each coil fires directly into its corresponding spark plug, controlled by the ECU.
The ECU uses data from the crankshaft and camshaft sensors to precisely control the timing
and duration of the spark for each cylinder.
This setup eliminates the need for high-tension leads and reduces the chance of misfires and
electrical losses.
2.3 Scope of application
+ Distributor
Commonly used in older vehicles before the 1980s.
Simple and cost-effective but prone to wear and mechanical failure.
+ Distributorless Ignition System (DLI) Electronic Ignition
Widely used in modern vehicles from the 1990s onward.
More reliable and maintenance-free compared to distributor systems.
Offers improved ignition timing control and efficiency.
+ Direct Ignition System (DIS).
Predominantly used in high-performance and modern vehicles.
Offers the highest precision and efficiency among ignition systems.
Ideal for engines requiring precise ignition timing and those with complex combustion
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chamber designs.

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