Basic Engine Operation

1
Basic Engine Operation Construction
Purpose of an engine - To create power for a
specific use!
Use for What?
Purpose of an Piston type engine - To create
power for a specific use and convert
reciprocating power to rotary power
How do you create Power?
Easy !!
A Potato Gun !!! How does it work!!
Converting reciprocating power to rotary power is
done with three basic parts
Its just like riding a bike !
What are other uses for straight line power ?
Rotary Power is more usefull !
2
External Combustion or Internal Combustion
Combustion the act or process of burning,
creating pressure for a specific use!
External Combustion
Pressure/Power created outside of the engine
Ie Steam Engines
Web Link
Internal Combustion
Pressure/Power created inside of the engine
Ie Four Stroke Cycle Engines
Web Link
3
Creating Internal Combustion
Vacuum Low Pressure Area, air moves High to
Low
4
Creating Internal Combustion
Compressing the A/F mixture makes it more
volatile! Why?

• Compression Creates
• Energy
• Heat
• An super active
• A/F mixture

Compress the A/F to much add !
Pre-Ignition!
5
Creating Internal Combustion
Ignition starts the burning of the A/F mixture
Power burning A/F mixture
Combustion Completed
6
Creating Internal Combustion
Remove the burnt A/F Mixture via pressure
Start Over! How?
Done!
7
Welcome to the Four Stroke Cycle
Intake
Compression
Power
Exhaust
Animated 4 Stroke
8
Basic Engine Terminology
9
The Four Stroke Cycle
Intake - Intake valve opens, piston travels from
TDC to BDC, creating a vacuum, drawing in
air/fuel mixture into the combustion camber.
Intake valve closes.
Compression - Both valves closed, piston travels
from BDC to TDC compressing the air/fuel mixture.
A volatile mixture, and heat are created.
Power - air/fuel mixture is ignited and begins to
burn, and expands. the pressure forces the
piston down from TDC to BDC causing the
crankshaft to turn.
Exhaust - exhaust valve opens, piston moves from
BDC to TDC forcing out the burnt gases remaining
from the created power. Exhaust valve closes
CYCLE REPEATS
10
Engine Classification
Number of Cylinders
.
Cylinder Arrangements
Valve Train types
Fuel Types
Cooling System
Ignition Types
11
Number of Cylinders Cylinder Arrangements
Inline
V-Type
Opposed
2, 4, 6
2, 4,6, 8, 10,12, 16
1, 2, 3, 4, 5, 6, 8
Animation Link
Cylinder Numbering
Firing Order
the order in which each cylinder begins its power
stroke
12
Other Piston Cylinder Arrangements
Radial
W12
Radial Animation
13
Engine Classification
Number of Cylinders
.
Cylinder Arrangements
Valve Train types
Fuel Types
Cooling System
Ignition Types
14
Valve Train Types
L Head
T Head
F Head
I Head
15
How valves Open and Close
Briggs Stratton L Head Design
Mechanically with A Cam Lobe
Valve Timing with gear ratios
Camshaft
Crankshaft
Camshaft
Crankshaft
1 1
1 2
16
How valves Open and Close
T Head
F Head
I Head
Animated I Head
17
How valves Open and Close
Overhead Camshaft
DOHC
Double Over Head Cam
18
Engine Classification
Number of Cylinders
.
Cylinder Arrangements
Valve Train types
Fuel Types
Cooling System
Ignition Types
19
Fuel Types
Advantages
Disadvantages
- different octane levels - availability
- highest polluting
Gasoline

• cost
• low polluting

• power loss 10
• availability

Propane

• power loss 20
• availability
• - carrying danger

- cost, cheapest - very low polluting
Natural Gas

• high octane
• - Very low polluting

• high cost
• - poor fuel economy

Alcohol

• cost, better fuel economy
• lots power/torque
• - long lasting

• high polluting
• engine cost
• - noise / low RPM

Diesel
20
Engine Classification
Number of Cylinders
.
Cylinder Arrangements
Valve Train types
Fuel Types
Cooling System
Ignition Types
21
Cooling System / Ignition Type
Air Cooled
Spark
Liquid Cooled
Compression
22
Other Engine Types
Diesel Engine
Diesel Fuel oil by product from the crude oil
refining process.
- rated by cetane number, difficult to ignite
Compression Air Only Creating Heat
Power Hot Air Ignites Injected Diesel
Exhaust Burnt A/F Pushed Out
Intake Air Only
23
Other Engine Types
Diesel Engine

• Diesel Injectors must
• Enter correct amount of fuel
• Be at the right time
• Control the rate of fuel
• Start and stop abruptly

Advantages - cost, better fuel economy - lots
power/torque - long lasting

• Disadvantages
• slow acceleration
• low RPM
• - engine cost
• fuel system repairs
• noise

24
Other Engine Types
Two Stroke Cycle
Basic operating principles - similar to a 4
stroke, operating principles of Intake,
Compression, Power and Exhaust. - the above
principles are completed in two strokes instead
of four, stages are combined
How do you combined 4 strokes into 2 ?
Exhaust
Intake
Compression
Power
25
Other Engine Types
Intake
Two Stroke Cycle
Intake - intake port is cleared by the piston -
Air/Fuel mixture is pushed into the combustion
chamber.

• Compression
• only occurs for aprox. 1/2
• of the piston movement up

Compression
26
Other Engine Types
Power
Two Stroke Cycle
Power - only occurs for aprox. the first 1/2 of
the piston moving down.
Exhaust - exhaust port is cleared by the
piston. exhaust to escapes from the pressure of
the power stroke
Exhaust
CYCLE REPEATS
Animated 2 stroke
27
Other Engine Types
Two Stroke Cycle
Other Operating Principles
How is the A/F pushed into the combustion camber?

• A/F mixture is drawn into the crankcase as the
  piston is moving up during the power stage by a
  vacuum in the crankcase, drawing in the
  air/fuel/oil mixture

Animated 2 stroke
As the moves down on the power stage, pressure is
created in the crankcase, therefore forcing the
A/F mixture into the combustion camber

28
Other Engine Types
Two Stroke Cycle
Disadvantages - high wear rate - low torque -
lubrication needs to be mixed
or injected - high in pollutants

• Advantages
• less moving parts,
• no valves
• - runs at any angle
• high revving
• fast acceleration

29
Other Engine Types
Two Stroke Diesel
Similar operating principle of the two stoke
gasoline engine.
However the crankcase is not used to create
pressure! Air is forced by a blower!
30
Other Engine Types
Two Stroke Diesel

• Advantages
• - better fuel economy
• - lots power/torque
• - long lasting
• - less moving parts
• higher revving
• faster acceleration

• Disadvantages
• - engine cost
• - fuel system repairs
• - noise

31
Other Engine Types
Rotary Combustion
Not a reciprocating motor - motion of operation
is already in rotary motion
Turbine / Jet engines
WANKEL ENGINES
Bingo! A Wankel!
Imagine a spinning triangular block inside a
can! The cambers on each side do not change
volume.
However! If the triangle is turning of centre,
the camber change volume as it rotates.
32
Other Engine Types
Rotary Combustion
Basic Operating Principles Stages
Stage 1 - rotor clears intake port, chamber
increases in size, creating a vacuum drawing in
A/F mixture
Other operating principles - three chambers
acting at the same time doing different stages -
some motors wth two rotors therefore six power
thrust for one revolution - power to crankshaft
done with gears on an eccentric - 3 to 1 ratio of
rotor to crankshaft rotation
Stage 2 - rotor continues to rotate, intake port
closed off, chamber begins to compress A/F mixture
Stage 3 - A/F mixture ignited by spark plug,
burning creating power against rotor continuing
rotary motion
Stage 4 - turning rotor uncovers exhaust port,
forcing out exhaust gases as chamber is
decreasing STAGES REPEAT
Wankel Animation
33
Other Engine Types
Rotary Combustion
Advantages - fewer moving parts - less power
loss to friction - 1/2 size / hp of piston
engine - almost vibration less - quite running -
great acceleration - constant torque - high RPM
obtained

• Disadvantages
• rapid wear of appex seals
• repair costs
• - poor fuel economy
• - high in air pollutants