Basic Engine Operation & ConstructionPurpose of an engine - To create power for a specific use!Use for What?How do you create Power?A Potato Gun !!! How does it work!!

What are other uses for straight line power ?

Purpose of an Piston type engine - To create power for a specific use and convert reciprocating power to rotary power

Converting reciprocating power to rotary power is done with three basic partsEasy !!

It’s just like riding a bike !

Rotary Power is more usefull !

External Combustion or Internal CombustionCombustion: the act or process of burning, creating pressure for a specific use!

External Combustion: Pressure/Power created outside of the engine

Ie: Steam Engines

Internal Combustion: Pressure/Power created inside of the engine

Ie: Four Stroke Cycle Engines

Web Link

Web Link

Creating Internal CombustionVacuum – Low Pressure Area, air moves “High to Low”

Creating Internal Combustion

Compressing theA/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!

Creating Internal CombustionPower – burning A/F mixture

Ignition starts the burning of the A/F mixture Combustion Completed

Creating Internal CombustionStart Over! How?

Remove the burntA/F Mixture via pressure Done!

Welcome to the Four Stroke Cycle

Intake Compression Power Exhaust

Animated 4 Stroke

Basic Engine Terminology

The Four Stroke CycleIntake - 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

Engine Classification

Number of Cylinders:

Cylinder Arrangements:

Valve Train types:

Ignition Types:

Cooling System:

Fuel Types:

.

Number of Cylinders & Cylinder Arrangements Inline: V-Type Opposed

1, 2, 3, 4, 5, 6, 8 2, 4,6, 8, 10,12, 16 2, 4, 6

Animation LinkCylinder Numbering

Firing Order: the order in which each cylinder begins its power stroke

Other Piston Cylinder Arrangements

Radial W12

Radial Animation

Engine Classification

Number of Cylinders:

Cylinder Arrangements:

Valve Train types:

Ignition Types:

Cooling System:

Fuel Types:

.

Valve Train Types

T Head

F Head

L Head

I Head

How valves Open and CloseBriggs & Stratton L Head Design

Mechanically withA Cam Lobe

Valve Timing with gear ratio’s

1 : 1 1 : 2

CamshaftCamshaft

Crankshaft

Crankshaft

How valves Open and CloseT Head

F Head

I Head

Animated I Head

How valves Open and Close

DOHCDouble Over Head Cam

Overhead Camshaft

Engine Classification

Number of Cylinders:

Cylinder Arrangements:

Valve Train types:

Ignition Types:

Cooling System:

Fuel Types:

.

Fuel Types

Gasoline

Propane

Natural Gas

Alcohol

Diesel

Advantages Disadvantages

- different octane levels- availability

- highest polluting

- cost- low polluting

- power loss 10%- availability

- cost, cheapest - very low polluting

- power loss 20%- availability- carrying danger

- high octane- Very low polluting

- high cost- poor fuel economy

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

- high polluting- engine cost- noise / low RPM

Engine Classification

Number of Cylinders:

Cylinder Arrangements:

Valve Train types:

Ignition Types:

Cooling System:

Fuel Types:

.

Cooling System / Ignition Type

AirCooled Spark

LiquidCooled Compression

Other Engine TypesDiesel Engine

Diesel Fuel oil – by product from the crude oil refining process. - rated by cetane number, difficult to ignite

IntakeAir Only

CompressionAir Only

Creating Heat

PowerHot Air IgnitesInjected Diesel

ExhaustBurnt A/F

Pushed Out

Other Engine TypesDiesel 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

Other Engine TypesTwo 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 ?

Intake Compression Power Exhaust

Other Engine TypesTwo Stroke Cycle

Intake

Compression

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

Other Engine TypesTwo Stroke Cycle

Power

Exhaust

Power - only occurs for aprox. the first 1/2 of the piston moving down.

CYCLE REPEATS

Exhaust - exhaust port is cleared by the piston. exhaust to escapes from the pressure of the power stroke

Animated 2 stroke

Other Engine TypesTwo Stroke Cycle

Other Operating Principles

-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

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

How is the A/F pushed into the combustion camber?

Animated 2 stroke

Other Engine TypesTwo 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

Other Engine TypesTwo 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!

Other Engine TypesTwo Stroke Diesel

Disadvantages

- engine cost- fuel system repairs- noise

Advantages

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

Other Engine TypesRotary Combustion

Not a reciprocating motor - motion of operation is already in rotary motion

Turbine / Jet enginesWANKEL ENGINES

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.

Bingo! A Wankel!

Other Engine TypesRotary Combustion

Wankel Animation

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

Basic Operating Principles – Stages

Stage 1 - rotor clears intake port, chamber increases in size, creating a vacuum drawing in A/F mixture

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

Other Engine TypesRotary 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