Engines

Control PowerCVHS

Introduction

We will be examining several types of engine converters that are commonly used

Many are used in the Transportation sector

We call them “Heat Engines” because: convert thermal energy from fuel to mechanical

energy for motion

Classifications are based on: location of combustion, type of combustion, and

type of internal motion

Common Classifications

IC or ICE combustion is internal combustion directly touches the parts

that must be moved example: car engine

EC or ECE combustion is external example: boiler (steam engine)

Common Classifications

Intermittent Combustion Engine combustion starts and stops many times examples: car engines - gas and diesel

Continuous Combustion Engine example: rocket engine

Reciprocating Engine classification based on internal part

motion examples: gas and diesel engines

Common Classifications

Rotary Engines another parts motion

classification internal parts have a

continuous rotation movement examples: Wankel and Turbine engines

Others Classifications Cycles, Cooling Sys, Fuel Sys, Ignition

Sys

Heat Engine Parts and SystemsCylinder Block Foundation All other components are attached

to itCylinders internal holes in the block (combustion chambers) Autos: 2, 3, 4, 5, 6, 8,10 ,12Autos: 3, 4, 6, 8, 12

Cylinder Head houses the valves, ports and spark plugs for the

engineValves and Ports purpose is to allow air and fuel to enter and leave

the combustion chamber

Heat Engine Parts and Systems

Pistons the round piece that slides up

and down within the cylinderConnecting Rod and Crankshaft CR is attached from the bottom of the

piston and attaches to the crankshaft the crankshaft converts reciprocating

motion to rotaryCombustion Chamber the area inside the Cylinder

Head and Block

Heat Engine Parts and Systems

Camshaft the mechanism used to open

the valves at the right times

it is driven by the crankshaft which is connected to the connecting rod (timed to the crankshaft)

may be mounted in the block or on top of the block (OHC - Overhead camshaft) (DOHC - Dual Overhead Camshaft)

Heat Engine Parts and Systems

Flywheel connected to the end of

the crankshaft to smooth out any intermittent motion (remember we have intermittent combustion)

utilize Newton’s Law “An object in motion tends to

remain in motion, whereas an object at rest tends to remain at rest”

Heat Engine Parts and Systems

Carburetor/Fuel Injection mixes the air and fuel in the right

proportion

Engine Systems

Cooling: liquid and air - keep temp constant Fuel: monitor and control the feed Lubrication: reduce friction Ignition: providing the spark for combustion Starting: crank (battery & dc starter motor) Charging: replenish the battery Air/Exhaust: feed air in an out Computer Controlled: to aid - precision of

sys. Fuel, ignition, etc.

Pollution Control: environmental

Combustion Requirements

1) AIR 2) FUEL 3) SPARK 4) TIMING 5) COMPRESSION

Bore & StrokeBore & Stroke help determine the size: Bore - diameter of the cylinder Stroke - distance the piston travels from

TDC to BDC determined by design of the crankshaft center of the crankshaft to the center of the

crankpin multiplied by 2 = the stroke distance

Four Stroke Engine DesignOne of the most popular reciprocating-type heat engines Intake: piston moves downward with intake

valve open Compression: piston moving upward, all valves

are closed Power: after the spark,

power occurs downward Exhaust: as the piston

moves upward again, exhaust valves open

Two-Cycle Engine DesignDoes not use standard valves like the 4-cycleOil is added to the Air-Fuel mixture because there is no oil in the crankcase as with the 4-cycle engine design

the oil acts as a lubricantCompression Stroke up

creates a vacuum and pulls in the fuel/oil mixture into the combustion chamber (Crankshaft)

Ignition just before TDC, crankcase full, reed valve closedPower Stroke down

exhaust is vented out by pressure on the fuel in the combustion chamber from the piston

Advantages & Disadvantages of 2-Stroke

ADV: Very responsive (power pulse every rev.) Usually lighter than 4-cycle engines, fewer

parts Can be operated at varying angles of

operation no crankcase that holds oil

DISADV Not as efficient as 4 stroke Not as durable

Diesel Engine Design

Considered a 4 cycle, IC (can also have 2 cycle)Compression rather than spark ignition

Glow plug and block heaters used to pre-warm fuel and engine on cold starts

No carburetor (fuel injection) air enters on the intake stroke Fuel is injected during compression Extreme pressure (diesel engines

have very high compression ratios) & heat ignite fuel

Rotary (Wankel)

MAZDA Most popular during the 1970’sNot Reciprocating Rotors instead of PistonsNo valves (only the intake and exhaust ports)Intermittent combustion, spark ignition, rotary designFew moving parts = extremely high revs.