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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.