KINEMATICS OF COMBUSTION ENGINES

Reciprocating Engine

•The pressure forces of the working fluid acting on the piston are transmitted directly to the crankshaft via piston pin and connecting rod

Configuration of Engine

Displacement of crank radius

Displacement of connecting rod

Define:

Using Trigonometry Law:

0 1 2 3 4 5 60

10

20

30

40

50

60

70

80

Crank Angle (Rad)

Pist

on D

ispl

acem

ent (

mm

)

Lamda s = 0.9

Lamda s = 0.5

Lamda s = 0.2

a) Piston Travel

b) Piston Speed

::

{For small lamda - s}

0 1 2 3 4 5 6-5000

-4000

-3000

-2000

-1000

0

1000

2000

3000

4000

5000

Crank Angle (rad)

Pis

ton

Spe

ed (

mm

/s)

Lamda s = 0.5

Lamda s = 0.3

Lamda s = 0.1

c) Piston Acceleration

For the approximated formula:

Design of Flywheel

Assuming Rigid Shaft

Ti To

Primarily we want to know the overall performance of the flywheel.

-What should its moment of inertia be? -How do we match the power source to the load? -And what are the resulting performance characteristics of the system that we have selected?

An Example of a Flywheel Operating Conditions:

• A flywheel receives energy under a constant torque causing its shaft to rotate from 1 to 2. (Positive Torque)• The shaft rotates from 1 to 2. • The shaft rotates constantly from 2 to 3, under no torque.• The flywheel gives out energy under constant torque to operate a load.• The shaft speed drop from 3 to 4.