12-12-2012, 12:42 PM
Engine Balancing
Engine_Balancing[2].ppt (Size: 1.39 MB / Downloads: 304)
Overview
Engine balancing is one of the important aspects for smooth
operation of diesel engine.
Balancing helps in reducing engine vibration to an acceptable
limit.
Unbalanced engine is liable to excite severe vibration and
cause damage to engine components and ship structure.
Learning Objectives
Meaning of Balancing
Static Balancing
Dynamic Balancing
Partial Balancing of Engine
Complete Balancing of Engine
Static Balance
When a shaft carries a number of eccentric masses
and if the sum of the moments of all the masses
about the axis of rotation is equal to Zero for all
angular positions,
the shaft assembly is said to be in Static Balance
Dynamic Balancing
Dynamic balancing is a way of controlling vibrations by
arranging the overall summation of out-of balance forces and
couples cancels out or reduced to more acceptable value
There are two groups of forces and couples - related to:
revolving mass
reciprocating mass
Rotating mass balance is quite easily obtained by choice of
crank sequence and balance weight
Reciprocating mass balance is more complicated.
Second Order Moment Compensator
This eliminates the out-of-balance second order moment
The forces from the unbalanced reciprocating masses are the only forces that generate second order moments.
These forces act only in the vertical direction
The Lanchester balancer is a second order moment compensator and it consists of two counter rotating masses running at twice engine RPM
These counter rotating masses can be fitted at
the aft end of the engine, driven by the camshaft chain
the forward end of the engine, driven by auxiliary chain
both ends of the engine driven by gears