Engine Components and Basics

Question 1

Cylinder head

Answer 1

To seal the working fluid
Houses the inlets, outlets, spark plugs
Cast iron or Al in modern cars

Question 2

Cylinder

Answer 2

Guides the piston
Where combustion occurs
Most be cooled as in contact with hot products

Question 3

Cylinder liner

Answer 3

Inner wall of the cylinder
Purpose is to maintain heat in combustion chamber
Second purpose to reduce frictional loses

Question 4

Head gasket

Answer 4

To seal the joint between cylinder head and engine block
Prevent leakage of fluids

Question 5

Manifold

Answer 5

Supply airfuel mixture and collect exhaust gas

Question 6

Inlet/Exhaust valves

Answer 6

Regulate flow of fluid in and out of the cylinder
2 inlets and outlet for each cylinder
Sinusoidal operation

Question 7

Camshaft

Answer 7

Controls valve timings
Ontop of the cylinder head
Driven by the crank via timing belt

Question 8

Piston

Answer 8

Transfers combustion energy to the connecting rod
Compression of airfuel mixture
Gas tight seal that can slide freely
High thermal and wear resistance

Question 9

Piston Rings

Answer 9

Top and mid ring = compression rings, stop pressure loss

Bottom ring = oil ring, keeps oil out of combustion chamber and provides cooling

Question 10

Connecting rod

Answer 10

Connects piston to crank
Must be very strong
Good lubrication required to minimise frictional loses

Question 11

Crankshaft

Answer 11

Linear into rotational motion
Journals and counterweights for vibration minimisation
Connected to fly wheel and ring gear (used to start engine)
Can rotate freely

Question 12

Oil sump

Answer 12

Collect oil from engine
Repumps oil into the engine
Bolted to bottom

Question 13

Timing belt

Answer 13

Links the crank and cam shaft
Cam-crank ratio of 2:1

Question 14

Engine bearings

Answer 14

Used to reduce frictional loses throughout the engine
allowed to freely rotate

Question 15

Fly Wheel

Answer 15

Attached to crankshaft
On the other side is the clutch
Ring gear to start the engine

Question 16

Spark plug (SI only)

Answer 16

Produces spark that ignites airfuel mixture for combustion
1 per cylinder

Question 17

Carborator (SI only)

Answer 17

Not used anymore
Atomises the liquid fuel
Produces premixed airfuel mixture

Question 18

Port injectors (SI only)

Answer 18

Fuel injected into the intake manifold
Mechanically or electrically controlled

Question 19

Direct injectors (SI only)

Answer 19

Fuel injected into the cylinder
Fuel sprayed into combustion chamber at high pressure

Question 20

Fuel atomiser or injector (CI only)

Answer 20

Direct fuel injection into the cylinder
Different spray patters achievable
Many holes available

Question 21

Name the main engine layouts

Answer 21

Inline
V type -> more power as more cylinders for same space
Flat - mostly 2 stroke

Question 22

What is the typical firing order in a 4 cylinder engine

Answer 22

1432 or 1243

This is to achieve good cooling

Question 23

Cooling systems purpose

Answer 23

Liquid cooling system can be used to remove heat from the engine

Removed heat can be supplied to passengers

Question 24

Engine Sensors

Answer 24

Engine speed

Determine crank position and piston position
- hall effect and inductive sensors

Question 25

Micromechanical pressure sensors

Answer 25

Intake manifold pressure
boost pressure
ambient pressure and air density

so the ECU can change AFR for optimum performance depending on these…

Question 26

High pressure sensors

Answer 26

Measure fuel and break fluid pressure
Rail pressure sensors

Question 27

Temperature Sensors

Answer 27

Installed in cooling circuit
Air, engine oil, fuel, and exhaust
Important to understand if the engine is overheating
ECU takes measures to cool engine (increase AFR)

Question 28

Knock sensors

Answer 28

Vibration sensors to detect knock
Send info to ECU to adjust injection timing

Question 29

Lambda oxygen sensors

Answer 29

Measure oxygen content in the exhuast
Determines if lean or rich combustion
-> too little/no oxygen is stoich or rich
-> too much is lean

Want stoich conditions in SI and fuel lean in CI

Question 30

Actuators

Answer 30

Final control elements for the interface between electronic signal processor and the actual process

electric signal -> mechanical process

Question 31

what are the 4 strokes in combustion

Answer 31

intake -> inlet open, outlet closed

compression -> both close and gas is compressed

combustion -> both close, spark or auto-ignition

exhaust -> inlet closed, outlet open

Question 32

2 stroke engine vs 4 stroke engine

Answer 32

intake and compression together
power and exhaust together

lighter flywheel
no valves, just ports
thermal efficiency is comparatively low
greater cooling and lubrication
initial cost is lower
used in low cost applications