2. Introduction to IC engines
Invented in early 1680
First attempt by Christian Huygens
Converts heat energy produced by burning of
fuel to mechanical output.
Basically consists of a piston-cylinder
arrangement.
The expansion of air due to the heat produced
moves the piston inside the cylinder.
3. Classification of IC engines
Two main classifications:
Based on combustion
Spark Ignition [SI engines] (Eg: Petrol Engine)
Compression Ignition [CI engines] (Eg: Diesel
Engine)
Based on Number of strokes
Two stroke
Four Stroke
Six Stroke
4. Major areas of advancement
The vision behind evolving of IC engine was to
extract maximum power from the fuel while
reducing emissions and pollution from the
engine.
The main areas of advancement are:
Engine Design
Material Selection
Timing Controls
Fuel Injection And Combustion
The advances moves almost parallel and most
companies have their own versions of the
advances discussed here.
5. Engine Design
The early designs involved a single cylinder.
This caused a large amount of fluctuations in
power output.
So more number of cylinders were added to
reduce output fluctuations and size of engine
There are four types of engine designs used.
Inline
V Type
Flat Type
Radial Engines
6. Engine Design
Inline Engine
V Type Engine
Flat Engine
Radial Engine
7. Material selection
When selecting materials for engine, following
factors are considered
Weight of material
Melting point
Coefficient of expansion
Heat transmission power
Vibration and sound damping
The main metals used in engine manufacture
are
Grey Cast Iron
Aluminium
Magnesium
8. Use of Sodium in engines
A part of engine is hollowed and is filled with
sodium
When temperature of the part becomes 1600C
sodium melts
This molten state has better heat transfer that
solid metal
Sodium is mainly used in:
Sodium Valves (Exhaust Valves)
Piston Skirts
9. Timing controls
The Efficiency of engine is decided by the
timing of its sequential operation.
Timing of inlet and exhaust valves
Timing of the spark in SI engines
Timing of fuel injection in CI engines
Sequential operation of each cylinders in multi cylinder engine
In normal cases these timings are a design
parameter set at time of manufacture.
The goal of timing control is to change the
timings of engine while its working.
10. Variable Valve Timing (VVT)
At low rpm, the timing is adjusted for maximum
efficiency.
At high rpm, time the valve remains opened is
reduced while increasing the opening size.
This helps to pump more charge to cylinder
without creating backpressure or scavenching.
An electronic system uses a microcontroller to
adjust the solenoid valve.
11. Variable Valve Timing (VVT)
In a mechanical system, the input from crank
is given to a gear which is locked to the cam
using a pin.
When adjustment is needed, the pin is
removed magnetically and a stepper motor
adjusts the cam.
Used in many cars in various names
BMW Valvetronic, VANOS
Fiat Twin Cam VIS
General Motors VVT, DCVCP
Honda VTEC, i-VTEC
13. Active Valve Train
In active valve train, there will be two cams
designed for specific road conditions.
When the microprocessor detects a rough
terrain, the cam used will be the one for more
power.
But during cruising, the cam is switched to a
low power, high efficient cam using a cam
tapper.
Introduced first by Lotus Motors and later
developed by Nissan Motors.
14. Cylinder Deactivation
Cylinder deactivation is a derived form of
active cam switching.
In this method, while cruising a part of
cylinders are switched off by switching to a
cam without lobes.
This method is successful because of
following
Lesser fuel consumption
Less heat generation
Less power lost in managing other cylinders
This is mostly employed in V Type Engines.
15. Cylinder Deactivation
The cylinder is deactivated by
Keeping the inlet valve closed so that there is no
fuel flow
Keeping the exhaust valve open so there is no
work done in compression.
Some Companies using cylinder deactivation
are
General Motors V8-6-4 (Cadillac)
General Motors Active Fuel Management
DaimlerChrysler Active Cylinder Control (ACC) (for Mercedes-
Benz)
Honda Variable Cylinder Management (VCM)
16. Fuels and Fuel Injection
The fuels and its input to the engine highly
influences the emissions from the engines.
In SI engines a air-fuel mixture called charge
is introduced to the cylinder before
compression
In CI engines the fuel is injected after the
compression stroke to the cylinder. This helps
in attaining higher compression ratios.
In SI engines it is not possible because there
is a chance that the fuel may burn before
hand.
17. Direct Injection
With direct injection, the advantages of CI
engines can be obtained in SI engines also.
In direct injection, first the air is filled in the
cylinder. Then half way through the
compression stroke, a small amount of fuel is
injected to the cylinder to create a lean
mixture.
At the end of compression, just before the
spark the rest of fuel is injected to the head of
spark plug.
The burning of fuel occurs in a stratified
18. Direct Injection
Direct injection has many advantages such as
No need of carburetor
Easy design of manifold
Better compression is achievable
No case of knocking in engines
Lower NOx emissions
Due to stratified combustion leaner mixture can
be used which reduces the fuel consumption.
20. Superchargers
Consists of a compressor coupled to the
engine using a belt.
The output is directly connected to the engine.
As the engine rotates, the air is sucked in and
compressed which is then fed to the cylinders.
Increases the amount of oxygen given to
engine thus helps in better burning.
Is a must in aircrafts flying at high altitudes
were air is less dense.
21. Turbochargers
Is a derived form of supercharger
Consists of a turbine and a compressor
coupled in a shaft.
Instead of using the power from engine to turn
the compressor, the exhaust is used to turn the
turbine which rotates the compressor.
Turbochargers can only act at high velocity
exhaust so they need some time to start up in
cold start. This time is called as turbo lag.
22. Six Stroke Engines
The invention of six stroke engines was for the
following reasons:
Less weight to power ratio
Less scavenching
Less moving parts
More power and fuel economy
Obtain freedom in designing
Better cooling
Six stroke engines are developed in two
different ways
23. Air/Water injection to Cylinder
In this method air or water is injected to the
cylinder at the end of exhaust stroke.
The fluid absorbs the heat and expands
providing another power stroke. An exhaust
stroke is provided to removed the fluid from
cylinder.
Three recognized names in this section are:
Bajulazsix stroke engine (Preheating of air)
Velozeta six stroke engine (Injection of air)
Crower six stroke engine (Injection of water)
24. Opposed Piston Engines
This model uses two pistons working in and
cylinder.
The pistons are used to open and close ports
just like a two stroke engine.
The working of opposed pistons provide better
compression.
The pistons have either a change in speed or
have a phase shift between them.
Some engines in this section are:
BeareHead Engine
M4+2 engine
25. References
en.wikipedia.org
www.greencar.com
www.mitsubishi-motors.com
www.bmw.com/com/en/insights
Elements of IC Engines, Rogowsky, Tata
McGraw hill
Internal Combustion Engines, Mathur &
Metha, Vol I&II Pergamon Press
