"BALANCE SHAFT CALCULATION"
"BALANCE SHAFT CALCULATION"
(OP)
Could anybody please help?
I am using the Bosh Automotive Hand book to calculate the necessary mass for a 4 cylinder engine.
I calculated the Oscillating mass, using the sum of the piston mass and 1/3of the Conecting rod mass.
I calculated the Rotating mass using the crank mass plus 2/3 of the connecting rod mass,
then as the book says I calculate the 2nd order free forces of inertia as being
4*mo*r*w^2*lambda*cos(2alpha)
What now?
I need 2 balance shafts rotating opposite directions at double the crank speed.
But what is the excentric mass ?
I am using the Bosh Automotive Hand book to calculate the necessary mass for a 4 cylinder engine.
I calculated the Oscillating mass, using the sum of the piston mass and 1/3of the Conecting rod mass.
I calculated the Rotating mass using the crank mass plus 2/3 of the connecting rod mass,
then as the book says I calculate the 2nd order free forces of inertia as being
4*mo*r*w^2*lambda*cos(2alpha)
What now?
I need 2 balance shafts rotating opposite directions at double the crank speed.
But what is the excentric mass ?





RE: "BALANCE SHAFT CALCULATION"
http://autozine.kyul.net/technical_school/engine/smooth2.htm
It might be of some help
RE: "BALANCE SHAFT CALCULATION"
Their centrifugal forces should counterbalance the maximum 2nd order free forces (in Top and Bottom DCs) you have already calculated.
Centrifugal force of rotating excentric mass is: Fc = m*r*w^2
where:
m is amount of excentric mass (the both masses in this case)
r is distance between axis of rotation (balance shaft axis) and CG of excentric mass
w is angular speed of balance shafts
In your case variables (unknown) are m and r so you may play with those quantities (having in mind limiting factors, space for sure) to equalize the Fc with the max 2nd order free force.