MBD Simulation on IC Engine Valve Train
OBJECTIVE
In this project, the main objective is to model an IC engine valve train which consists of essential parts such as a cam, push rod, rocker arm, valve mount, and valve, then assemble them in SolidWorks. Then run the motion analysis to find the contact force encountered between the parts(between cam and push rod, push-rod and rocker arm, and rocker arm and valve) and explain the results.
THEORY
A valve-train or valve train is a mechanical system that controls operation of the valves in an internal combustion engine, whereby a sequence of components transmits motion throughout the assembly. A conventional reciprocating internal combustion engine uses valves to control the flow of the air/fuel admix into and out of the combustion chamber.
A typical valve-train consists of valves, rocker arms, push-rod, lifters, and cam. Valve-train opening/closing and duration, as well as the geometry of the valve-train, controls the amount of air and fuel entering the combustion chamber at any given point in time. Valve-trains are built in several configurations, each of which varies slightly in layout but still performs the task of opening and closing the valves at the time necessary for proper operation of the engine.
A typical Valve-train which describes each part is shown below.
CASE 1:- Motion analysis for cam lift 3.5mm:
Valve displacement:
Contact force between cam and push rod:
Contact force between pushrod and rocker arm:
Contact force between rocker arm and valve:
Contact force between rocker arm and valve (x component alone):
CASE 2:-
Motion analysis for cam lift 6mm:
Valve displacement:
Contact force between cam and push rod:
Contact force between pushrod and rocker arm:
Contact force between rocker arm and valve:
Contact force between rocker arm and valve (x component alone):
Conclusion:
As we can observe from the above graphs contact force between all the components are nearly same in both the cases.
But in the contact force of rocker arm and valve magnitude value and the force along x-axis is different, infact the force is negative and inverse this is because the force along the x axis is frictonal force and rocker arm is tend to slide on the valve surface which is opposite to the input.
By neglecting the interference we can get the smoother graph