Week 3.2

Question 1

Derive the equation for the acceleration and velocity of a piston.

Answer 1

Answer on onenote

Question 2

Draw the free-body diagram of a piston, conrod and crank. Derive the equation for the side thrust force, load force, ft and fn. What is the equation for engine torque?

Answer 2

Answer on onenote

Question 3

What is the equation for overturn torque?

Answer 3

-Fc *h = -T

Question 4

Name three different types of valvetrains, and draw them.

Answer 4

Overhead valve, single overhead camshaft, double overhead camshaft.

Question 5

What are some valvetrain requirements?

Answer 5

-Provide max volumetric efficiency
-Prompt and swift opening of valves
-maximize flow area
- minimalize weight
-minimal fictional losses

Question 6

What are some pros and cons of increasing the number of valves?

Answer 6

Pros:
-Increased flow area
-Better volumetric efficiency
-lighter valves
Cons:
-Higher costs
- Increased friction losses

Question 7

Compare the belt drive to the chain drive.

Answer 7

Chain drive:
-higher load capacity
- durable and reliable
-narrow in dimension- more space efficient
-Expensive
Belt drive:
- Cheaper
-less reliable
- more axial space required
-quieter

Question 8

Draw the valve timing clock.

Answer 8

Answer on onenote

Question 9

Describe changes that can be made to the valve timing clock to get low emissions

Answer 9

IVO- Reduced advance to prevent short cut between intake and exhaust
IVC- Reduced delay for low and medium speed ranges to prevent back flow into intake port
EVO- Reduced advance to allow for more complete combustion - medium to low speed ranges
EVC- Reduced delay for more EGR to control NOX, EGR allows for this by reducing the concentration of air in the intake, so less NOx is produced from this reaction.

Question 10

What efficiency can valve timing affect in an engine?

Answer 10

Volumetric efficiency

Question 11

Draw diagrams to highlight how valve timing changes with engine speed.

Answer 11

On Onenote/canvas