Question

When length the of crank and connecting rod is changed (i.e crank of length is changed by keeping connecting rod length constant and in other case connecting rod length is changed by keeping the crank length constant) what implications does it have on the reciprocating engine?

Answer 1

1.Longer rods invariably drive the pin position higher within the piston wherever it intersects the oil ring groove. Piston makers like Diamond supply a straightforward resolution with AN oil ring support rail. Support rails do a superb job and permit for terribly short piston heights.

2.Longer rods will improve rod stroke magnitude relation, reducing thrust loading on the piston. a preferred thought is that rod length affects displacement, that it doesn't. solely cylinder bore ANd shaft stroke alter the displacement of an engine.

The stroke length is sort of perpetually chosen 1st because it relates to the bore and stroke combination for the required displacement. Rod length is typically such as next supported the appliance. Theory on this is often widedebated and infrequently contradicting, however as a rule, shorter rods square measure typically chosen to achievea a lot of speedy departure from TDC because the piston starts down the bore. This opens a bigger cylinder filling house a lot of quickly so a high rate intake system will begin filling the cylinder quicker. it's typically accustomedenhance throttle response on applications that square measure oftentimes throttled.

3.Pistons with shorter rods reach TDC a lot of briskly and don’t loaf around long before they depart fleetly. The piston achieves most rate sooner and at less crank angle that reduces cylinder volume exposure at the purpose of mostpressure differential. applicable valve temporal order is needed to confirm optimum potency below these conditions. Since the piston achieves most rate sooner, the valve may be opened sooner to require advantage of the cylinder pressure differential. Less overall cylinder volume is exposed at now, however the first initiation of flow can chase the piston down the bore as volume exposure chop-chop will increase. this is often usually spoken because the piston tugging tougher on the charge thanks to its enhanced acceleration.

4.The block dimension from the middle line of the most bore dictates the ultimate stack length for the crank, rod, and piston assembly. that features the rod length, the stroke length and therefore the pin height. Rod length and pin height will may be juggled in line with the appliance, however the ultimate dimension is usually mounted by the block height.