This document provides an overview of electronic control systems in high-tech vehicles. It discusses the electronic control module that receives sensor data and controls various systems. It describes the electronic fuel injection and ignition systems that are controlled by sensors and the ECM to optimize fuel efficiency and reduce emissions. It also discusses the electronic exhaust system and how catalytic converters use oxidation and reduction catalysts to reduce harmful emissions exiting the vehicle.
2. INDEX
ABSTRACT
INTRODUCTION
ELECTRONIC CONTROL MODULE
ELECTRONIC INJECTION SYSTEM
ELECTRONIC EXHAUST SYSTEM
ADVANTAGES AND LIMITATIONS
CASE STUDY
FUTURE PROJECTIONS
CONCLUSION
BIBLIOGRAPHY
3. ABSTRACT
To cope up the burning problem of high priced and vanishing
fossil fuels; with research in renewable energies, we should think
for utilization of present amount of fuels in most efficient way.
This need gives rise to advancement in design, construction and
control of automotive engines. This has given rise to new
generation of more developed, light, fuel efficient “High Tech”
vehicles. Recent innovations in engine design and control have
been adopted very widely and rapidly.
The principle of Electronic Fuel Injection System is, the
different sensors like TPS, CPS senses the changes in engine
assembly and send electric signal to Electronic Control Module
(ECM) which continuously calculates how much fuel is to be
injected to achieve stoichiometric combustion. In the Ignition
System, Knock, Throttle Position Sensors feed corresponding
information to computer which decides correct timing of spark.
4. This system of spark ignition can develop 47,000 V or more and
produces longer and correct timed spark which ignites leaner air fuel
ratios for better fuel economy and reduces exhaust emission. In Exhaust
System, oxidizing and 3-way catalysts reduce harmful combustion
products like NOx, CO from exhaust gas and protect environment from
these gases by reducing them up to 90% along with reducing exhaust
noise by electronic mufflers.
Advantages of computer controlled engines are improvement in fuel
economy, improved reliability, system failure diagnosis, warning of
engine malfunctioning. Most of recent vehicles are now equipped with
electronic ignition systems. A few of these include electronic engine
control and management to which we are now familiar as VTi, DTSi,
DICOR, AMI engines; sequential port injection, multiport fuel injection
and throttle body fuel injection. Suitable combinations of advanced
control systems and alternate fuels in vehicles will surely solve the most
critical problem of fossil fuel up to some extent.
5. 1) INTRODUCTION
Automobile – It can be defined as self propelled vehicle used primarily
on public roads but adaptable to other surfaces.
First gasoline four stroke engine was developed by Nikoluas August
Otto (Germany) in year 1876. Since then, there have been continuous
developments in world of automobiles. But along with better mobility
and job creation, automobiles have brought noise and air pollution. At
present, fossil fuels account for about 77% of the global energy
consumption.
It is universally known that this pattern of energy consumption is not
sustainable. These needs give rise to advancement in design,
construction and control of automotive engines. The automobile
industries and governments in all over the world are pursuing the
research and developments of advanced vehicles and fuel technologies
that could minimize present energy consumptions and environmental
effects of automobiles.
6. Need of Electronics in Automobiles: - In early days, all systems in
automobiles were controlled mechanically which often are not as accurate as
the emission laws require. Inaccurate fuel metering may cause excessive HC,
NOx and CO in exhaust gas which is due to improportionate air-fuel mixture.
It also consumes more fuel.
Thus computer control is introduced in automobiles. It is incharge of
monitoring engine emissions and adjusting the engine to keep emissions as
low as possible. The computer receives information from different sensors.
Using this information, the computer can control devices like the fuel
injectors, spark plugs (ignition) and the idle speed to get the best performance
possible from the engine while keeping emission low.
In this paper, we are concentrating on Fuel Control Systems in automobiles
as they have direct contribution in fuel economy and environmental safety.
Fuel Injection, Ignition, Exhaust Systems are the main components of
control system. All three systems are interrelated with each other and
controlled by preplanned computer installed above the glove box within the
passenger compartment called as ECM (Electronic Control Module).
7. 2) ELECTRONIC CONTROL MODULE (ECM):-
“This is unit of automobile computer system which can receive
signals, process them, make decisions and send commands that
control other devices”.
8. Following sensors monitor the engine, transmission, air-intake,
exhaust, vehicle speed, fuel flow, and many other things that
affect engine performance.
The ECM uses this information to control fuel supply, the timing
of fuel injections, and the mix of fuel and air in the engine’s
combustion chambers.
Modern ECMs also control the engine’s ignition system, which
ignites fuel in the combustion chambers at precisely timed
intervals to operate the engine efficiently.
Such systems may be controlled by single engine computer or by
separate computers.
10. 3) ELECTRONIC FUEL INJECTION SYSTEM:-
In trying to keep up with emission laws and fuel efficiency, the fuel
system used in modern cars has changed a lot, over the years. The fuel-
injection system replaces the carburetor in most new vehicles to provide
more efficient fuel delivery system. The components of an electronic
fuel-injection system include injectors, a pump that delivers fuel from a
storage tank to the injector, a variety of sensors throughout the vehicle
and ECM.
There are two types of Injection system used in SI engines are
1) Multiport Fuel Injection (MFI): It has fuel injector in each intake
port.
2) Throttle Body Fuel Injection (TBI): It has one or two fuel injectors
located above the throttle valve.
Principle:-“Electronic sensors respond to varying engine speeds and
driving conditions by changing the ratio of fuel to air. The sensors send
a fine mist of fuel from the fuel supply through a fuel-injection nozzle
into a combustion chamber, where it is mixed with air. The mixture of
fuel and air triggers ignition”.
12. Working: - ECM continuously receives information about engine
speed, throttle position, intake air amount, pressure and temperature,
amount of oxygen from sensors. ECM checks this data with other data
stored in lookup tables in its memory. Then ECM decides when to open
the fuel injectors and for how long. The length of pulse opens injection
valve for the proper duration of time. In order to provide the correct
amount of fuel for every operating condition, the engine control unit
(ECU) has to monitor large number of input sensors. Here are some of
them:-
Mass Airflow Sensor – It measures flow rate of air by speed density or
air flow metering and provides electrical output to ECM that is
proportional to flow rate of air entering the engine.
Coolant Temperature Sensor – It is a thermistor. It continuously
reports ECM about engine coolant temperature. It allows the ECU to
determine when the engine has reached its proper operating temperature.
13. Oxygen sensor – It is installed in exhaust manifold and measures
amount of oxygen in exhaust gas. It works by comparing the oxygen
content of exhaust gas to that of outside air and produces small voltage
varying with amount of oxygen and sends to ECM. So the ECM can
determine how rich or lean the fuel mixture is and make adjustments
accordingly.
Throttle Position Sensor – It is mounted on throttle body monitors the
throttle valve position which determines how much air entering into the
engine so the ECU can respond quickly to changes, increasing or
decreasing the fuel rate as necessary
Manifold Absolute Pressure Sensor – It monitors the pressure of the
air in the intake manifold. The amount of air being drawn into the
engine is a good indication of how much power it is producing and the
more air that goes into the engine, lower the manifold pressure, so this
reading is used by ECM to gauge how much power is being produced.
Engine Speed Sensor – It reports about speed of crankshaft. ECM uses
this data to control fuel metering, ignition spark advance and the shifting
of electronic automatic transmission.
14. 5) EXHAUST SYSTEM
To solve burning problem of pollution, the governments have
created clean-air laws. To keep up with these laws, automakers have
made many refinements to car engines and fuel systems. In order to
reduce emissions, modern car engines carefully control the amount of
fuel they burn.
The main emissions of a car engine are Nitrogen gas (N2), Carbon
dioxide (CO2), Water vapor (H2O). These emissions are not that much
harmful. But because the combustion process is never perfect; some
smaller amounts of more harmful emissions are also produced in car
engines which are:
Carbon monoxide (CO)
Hydrocarbons or Volatile Organic Compounds (HC)
Nitrogen oxides (NOx)
To reduce the emissions, there is a device called a catalytic converter,
which treats the exhaust before it leaves the car and removes a lot of the
pollution.
15. How Catalytic Converters Reduce Pollution?
Most modern cars are equipped with three-way catalytic converters.
"Three-way" refers to the three regulated emissions it helps to reduce - carbon
monoxide, HCs and NOx molecules. There are two main types of structures
used in catalytic converters - honeycomb and ceramic beads. Most
automobiles today use a honeycomb structure. The converter uses two
different stages of catalysts, a reduction catalyst and an oxidation catalyst.
Both consist of a ceramic structure coated with a metal catalyst, usually
platinum, rhodium and/or palladium.
The Reduction Catalyst (first stage)
It uses platinum and rhodium to help reduce the NOx emissions. When
an NO or NO2 molecule contacts the catalyst, the catalyst separates the
nitrogen and the oxygen in the form of N2 and O2. For example:
2NO => N2 + O2 or 2NO2 => N2 + 2O2
The Oxidization Catalyst (second stage)
Platinum and palladium catalyst oxidizes CO and hydrocarbons with the
remaining oxygen in the exhaust gas. For example:
2CO + O2 => 2CO2
16. The Electronic Control System (Third Stage)
It monitors the exhaust stream, and uses this information to
control the fuel injection system. This control scheme allows the engine
computer to make sure that the engine is running at close to the
stoichiometric point, and also to make sure that there is enough oxygen
in the exhaust to allow the oxidization catalyst to burn the unburned
hydrocarbons and CO.
Muffler: - An electronic muffler uses sensors to monitor the sound
waves of the exhaust noise. The sound wave data are sent to a computer
that controls speakers near the tailpipe. The system generates sound
waves 180 degrees out of phase with the engine noise. The sound waves
from the electronic muffler collide with the exhaust sound waves and
they cancel each other out, leaving only low-level heat to emerge from
the tailpipe.
17. ADVANTAGES OF COMPUTER CONTROLLED ENGINES:-
1) Longer spark can ignite leaner air fuel mixture.
2) The electronic ignition system is capable of over 500 sparks per
seconds and permitting engine speed more than 8000 rpm.
3) The higher voltage (>47,000 V) produces a hotter spark for cleaner
burning, longer plug life. 4) Increase in Fuel Economy and
Environmental Safety.
6) Improve reliability, System failure diagnosis, warning of engine
malfunctioning.
LIMITATIONS
1) These systems are very expensive and delicate.
2) These systems are difficult to repair.
3) Still it is difficult to lower amount of CO2 (carbon dioxide) emissions
as it is a known
greenhouse gas and contributing to global warming.
18. CASE STUDY
New DTSi engines utilize Dual Spark ignition for faster and better
combustion. The DTSi engine on the Bajaj Pulsar comes with Digital
CDI for optimum ignition timing and TRICS III ignition control system
to further optimize performance.
The DTSi (Digital Twin Spark Ignition) technology incorporates twin
sparkplugs at either ends of the combustion chamber for faster and better
combustion. Single sparkplug meant slower burning of the air-fuel
mixture and sub-optimal combustion chamber characteristics. This is the
Heart of the New Technology from Bajaj.
The digital CDI (Computerized Direct Ignition) in the new Pulsar,
which features an advanced eight-bit microprocessor, handles the spark
delivery. The programmed chip's memory contains the optimum ignition
timing for any given engine rpm. Working together with the (TRICS III)
it delivers the optimum ignition timing for varying load conditions.
19. FUTURE PROJECTIONS
The computer control will change the field of automobile dramatically
over next few years. Fuel cells, computerized spark-ignition and direct-
injection engines for conventional and hybrid electric vehicles (HEVs)
are promising options in coming years. DICOR, VTi engines,
turbochargers are related advancements in this field.
Upcoming BMW's Double-VANOS and Valvectronic technologies will
allow the engine to adjust the burning hydrogen/air or gasoline/air fuel
mixtures and also help prevent nitrogen oxide (NOx) emissions. The
automobiles, which will come out in coming years, will be the gleaming,
high-tech fruit of over 25 years of experimentation and innovation.
20. CONCLUSION
In this paper, we have seen main three systems of an automobile
engine which are controlled electronically. Fuel injection system
controlled by ECM can supply appropriate amount of fuel each time
according to the varying engine speed and conditions. Electronic
Ignition system can produce longer and high voltage spark for complete
combustion of fuel. Modern exhaust systems can sufficiently reduce
harmful pollutants and noise by incorporating the catalytic converters
and mufflers. By comparing these systems with conventional systems it
is clear that electronic control systems are going to lead the automobile
industry to the new generation of “Fuel Efficient and High-Tech”
vehicles.
21. REFERENCES
1) “AUTOMOTIVE ENGINES”: CROUSE & ANGLIN
2) “PRINCIPLES OF ELECTRICITY & ELECTRONICS for
AUTOMOBILES”: NORM
CHAPMAN.
3) “AUTOMOTIVE MECHANICS”: CROUSE & ANGLIN
4) “AUTOMOTIVE DIGNOSIS & TUNE-UPS”: JAMES A.
JOHNSON
6) http//www.sensorsweb.com
7) http//www.howstuffworks.com