MBD Simulation on IC Engine Valve Train
1.AIM:
To design the cam based on the given data, make the valuve train assembly which consits cam, pushrod(follower), rocker arm, valve mount, valve. Motion analysis is also performed based on the various cases and required plots areobtained for respective data.
2.INTRODUCTION:
A valvetrain or valve train is a mechanical system that controls operation of the intake and exhaust valves in an internal combustion engine.The intake valves control the flow of air/fuel mixture (or air alone for direct-injected engines) into the combustion chamber, while the exhaust valves control the flow of spent exhaust gasses out of the combusion chamber once combustion is completed.The valvetrain layout is largely dependent on the location of the camshaft.
3. 3d MODEL OF PARTS:
cam:
Pushrod (follower)
rocker arm:
valve stem & Valve mount:
final assembly:
4.MOTION ANALYSIS:
| Sl.No | CAM Lift (mm) | Speed (RPM) | Material |
| 1 | 3.5 | 1500 | Cast Carbon Steel |
| 2 | 6 | 1500 |
Cast Carbon Steel |
formula for cam lift:
Case i:
R1 = 12.5 mm R2 = 5 mm cam lift = 3.5 mm
substutuing the values in the formula,
3.5 = (L - 12.5)+5
L = 11 mm
plots obtained after motion analysis:
plot 1: contact force between the Cam and Push Rod
plot 2: contact force between Pushrod and Rocker Arm
plot 3: contact force between the Rocker Arm and Valve
case ii:
R1 = 12.5 mm R2 = 5 mm cam lift = 6 mm
substutuing the values in the formula,
6 = (L - 12.5)+5
L = 13.5 mm
plot 4: contact force between the Cam and Push Rod
plot 5: contact force between Pushrod and Rocker Arm
plot 6: contact force between the Rocker Arm and Valve
plot 7: contact force between the Rocker Arm and Valve at x direction
Results:
Thus the motion analysis is performed and the desired plots are obtianed.
ANSWER: The magnitude represents the net contact force acting between the parts while the x direction represent the contact force acting between the roceker arm and the value along the x axis. The rocker arm and the value has two contact frictional forces one is moving towarards the origin and another is moving away from the origin.Therefore the plots are oppostie to each other.
From the plots it is clear that the movement is smother in case ii cam design than the case i cam design.