AMT 214 (PRELIMS)
Piston Engine Fundamentals and Basic Parts • Spark plug
1. Mechanical, Thermal, and Volumetric Efficiencies - It ignites the compressed fuel/air mixture
2. Operating principles: by an electric spark
• Rotary Operating Cycles
• Diesel There are several engine operating cycles in use:
• 2 stroke 1. Rotary
• 4 stroke 2. Diesel
3. Piston displacement and Compression Ratio 3. 2 Stroke
4. Engine Configuration and Firing Order 4. 4 Stroke
Engine Requirements: Four-stroke Cycle
• Lightweight - Two complete revolutions of the crankshaft (720°)
• Reliable - Two revolutions of the crankshaft.
• Durable • Intake/induction
• Flexible - Piston moves down to BDC (bottom dead
• Balance center) by the rotation of the crankshaft, it
draws air and fuel in to the cylinder
• Weight per horsepower
through the intake port.
Reciprocating Engine
- It is a type of internal combustion engine that • Compression
derives its name from the back-and-forth - The piston moves up to TDC (top dead
movement, or reciprocating movement of the center), compressing the air and fuel
pistons. mixture.
Operating Principles • Power/Combustion
Internal Combustion Engine - As the piston travels through TDC (top
- It is a device for converting Heat energy into dead center) in the compression stroke
mechanical energy. the spark plug ignites the fuel and air
Basic Parts of an Internal Combustion Engine mixture, forcing the piston down.
• Cylinder • Exhaust
- It forms a part of the chamber in which - As the piston moves upward again from
the fuel and air mixture is compressed BDC (bottom dead center) it forces the
and burned. burnt air and fuel mixture out of the
• Intake Valve exhaust port.
- It is needed to let the fuel / air mixture go Nikolaus Otto – Originator of the Otto Cycle
inside the cylinder Four Stroke Valve Timing
TDC – Top Dead Center
• Exhaust Valve
BDC – Bottom Dead Center
- It is needed to let the burned fuel / air
Valve Lead
mixture or exhaust gassed go out from the
- It is when the valve opens BEFORE the IDEAL
cylinder.
opening time
• Connecting rod
Valve Lag
- It is the component that connects the
- It is when the valve remains open AFTER the
piston and the crankshaft.
IDEAL closing time
- Transfers the power from the piston to the
Valve overlap
crankshaft.
- Both valves open.
• Piston
Inlet Valve Timing
- It moves inside the cylinder that moves up
• The inlet valve opens somewhat earlier than the
and down or in reciprocating motion.
piston reaches TDC, so that by the time the piston
- It is to transfer force from expanding gas
reaches TDC the inlet valve is fully open.
in the cylinder to the crankshaft via a
• If the inlet valve is closed at BDC, the CYLINDER
connecting rod
will receive a charge (F & A mixture) less than its
• Crankshaft
capacity and the pressure inside the cylinder
- It is a rotating shaft that converts
Piston Engine Fundamentals and Basic Parts • Spark plug
1. Mechanical, Thermal, and Volumetric Efficiencies - It ignites the compressed fuel/air mixture
2. Operating principles: by an electric spark
• Rotary Operating Cycles
• Diesel There are several engine operating cycles in use:
• 2 stroke 1. Rotary
• 4 stroke 2. Diesel
3. Piston displacement and Compression Ratio 3. 2 Stroke
4. Engine Configuration and Firing Order 4. 4 Stroke
Engine Requirements: Four-stroke Cycle
• Lightweight - Two complete revolutions of the crankshaft (720°)
• Reliable - Two revolutions of the crankshaft.
• Durable • Intake/induction
• Flexible - Piston moves down to BDC (bottom dead
• Balance center) by the rotation of the crankshaft, it
draws air and fuel in to the cylinder
• Weight per horsepower
through the intake port.
Reciprocating Engine
- It is a type of internal combustion engine that • Compression
derives its name from the back-and-forth - The piston moves up to TDC (top dead
movement, or reciprocating movement of the center), compressing the air and fuel
pistons. mixture.
Operating Principles • Power/Combustion
Internal Combustion Engine - As the piston travels through TDC (top
- It is a device for converting Heat energy into dead center) in the compression stroke
mechanical energy. the spark plug ignites the fuel and air
Basic Parts of an Internal Combustion Engine mixture, forcing the piston down.
• Cylinder • Exhaust
- It forms a part of the chamber in which - As the piston moves upward again from
the fuel and air mixture is compressed BDC (bottom dead center) it forces the
and burned. burnt air and fuel mixture out of the
• Intake Valve exhaust port.
- It is needed to let the fuel / air mixture go Nikolaus Otto – Originator of the Otto Cycle
inside the cylinder Four Stroke Valve Timing
TDC – Top Dead Center
• Exhaust Valve
BDC – Bottom Dead Center
- It is needed to let the burned fuel / air
Valve Lead
mixture or exhaust gassed go out from the
- It is when the valve opens BEFORE the IDEAL
cylinder.
opening time
• Connecting rod
Valve Lag
- It is the component that connects the
- It is when the valve remains open AFTER the
piston and the crankshaft.
IDEAL closing time
- Transfers the power from the piston to the
Valve overlap
crankshaft.
- Both valves open.
• Piston
Inlet Valve Timing
- It moves inside the cylinder that moves up
• The inlet valve opens somewhat earlier than the
and down or in reciprocating motion.
piston reaches TDC, so that by the time the piston
- It is to transfer force from expanding gas
reaches TDC the inlet valve is fully open.
in the cylinder to the crankshaft via a
• If the inlet valve is closed at BDC, the CYLINDER
connecting rod
will receive a charge (F & A mixture) less than its
• Crankshaft
capacity and the pressure inside the cylinder
- It is a rotating shaft that converts
