Cylinder Kinematics : A Thinking Process of Artificial Animals

P M V SubbaraoProfessor

Mechanical Engineering Department

Means to Control Displacement, Velocity & Accelerations of

Cylinder Processes….

The Art of Positive Displacement Work

• Displacement of system provokes the process.

• The rate of change in instantaneous controls, decides the rates of changes of other thermodynamic variables.

• The brain of an animal controls the strain rates in Muscles…..

• How to design the basic brain of these devices?

Control Dominates the Strength

Control System of A Conventional I.C. Engine

Primary Thermodynamic Requirement:

How to select other geometrical parameters?

c

cd

V

VVr

Engine Geometry Vs Otto Cycle

1

11 rOttoth

11

11 1max

1min

rTrT

mRW

1

11

1 1max1

minmin

min

rTrT

T

VVpW cd

1

11

11

1max1

minmin

min

rTrT

Trr

VpW

d

Maximum Otto Cycle Volume to meet the Demand

11

min

max

2min

11

11

14

rrT

Trr

LBpW

1

1min

maxmin

2

11

114

1

rrT

Trr

p

WLB cycle

Engine Geometry Vs Diesel Cycle

1

1111

1c

cDiesel r

r

r

1min

1

max 11

rTr

rT

mRW c

11

min

max

2min

11

14

rr

r

T

Trr

LBpW c

Maximum Diesel Cycle Volume to meet the Demand

11

min

max

2min

11

14

rr

r

T

Trr

LBpW c

1

1

min

maxmin

2

114

1

rrr

TT

rr

p

WLB

c

DCycle

Cycle Volume Vs Cylinder Volume

• A given cycle can be met using m number of multiple cylinders if required.

mmLBmLB 22

• Any restriction on stroke length can be satisfied by using multi-cylinder engine.

• Why is this required?

m

LBLB mm

22

Review of History

• 1889 - Gottlieb Daimler built an improved four-stroke engine with mushroom-shaped valves and two V-slant cylinders.

• 1890 - Wilhelm Maybach built the first four-cylinder, four-stroke engine.

Effect of Stroke Length on Engine Kinematics

Engine Cylinder Geometry

• Squareness of the engine cylinder: RBS

)radius(crank 2 a

B

L

BRBS

Trending of Current Practice: Bore/Stroke Ratio

Bore – to –Stroke Ratio

Optimum Cylinder Geometry

• Identification of the optimum engine geometry that provides the best opportunity to have a highly efficient internal combustion engine is the first step in designing an engine.

• In-cylinder simulations have shown that the heat transfer increases rapidly above a bore-to-stroke ratio of about 0.5.

• Engine systems simulations have shown that the pumping work increases rapidly above a bore-to-stroke ratio of about 0.45.

• Engine friction models have shown that the crankshaft bearing and power-cylinder friction values, for the most part, cancel each other out for our opposed-piston, two-stroke engine.