Project

TITLE MBD SIMULATION ON IC ENGINE VALVE TRAIN

IIshank Gupta17 Aug 2019

TITLE: MBD SIMULATION ON IC ENGINE VALVE TRAIN

INTRODUCTION:
A valvetrain or valve train is a mechanical system that controls operation of the Valves in an IC engine, whereby a sequence of components transmits motion throughout the assembly used to control the flow of the air/fuel admix into and out of the combustion chamber.

Valvetrain consists of valves, rocker arms, pushrods and camshaft(s).

Valvetrain opening/closing and duration, as well as the geometry of the valvetrain, controls the amount of air and fuel entering the combustion chamber at any given point in time. Timing for open/close/duration is controlled by the camshaft that is synchronized to the crankshaft by a chain, belt, or gear.

Valvetrains 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. These layouts are differentiated by the location of the camshaft within the engine:

Cam-in-block The camshaft is located within the engine block, and operates directly on the valves, or indirectly via pushrods and rocker arms. Because they often require pushrods they are often called pushrod engines.
overhead camshaft The camshafts, depending on the design employed) is located above the valves within the cylinder head, and operates either indirectly or directly on the valves.
Camless This layout uses no camshafts at all. Technologies such as solenoids are used to individually actuate the valves.

OBJECTIVE:

Objective of this challenge was to design the parts based on the given cam lift formula perform a multibody analysiis on Ic engine valve train and study the valve lift and conntact forces devloped btw them.

REST OF THE PARTS remained same in both the cases only cam was changed based on the cam lift which was provided.

CASE 1:

CASE 2:

VALVE

PUSHROD

ROCKER ARM

VALVE STEM

ASSEMBLY

CASE 1: (GRAPH)

Contact force btw cam and push rod

Max force transmit is around 775 N when push rod comes down and around 200 N is transmitted duuring cam lift. Other forces and variotions are due to friction.

Contact force btw rocker arm and push rod

Similar to above graph.

Contact force btw rocker arm and valve (total magnitude)

Contact force btw rocker arm and valve - x direction

When we plot the contact forces in x direction, friction force btw the rocker arm and the valve head is main. due to sliding acttion of rocker arm over the valve it moves towards right nd left. causing positive and negative variations in the force.

the total magnitue graph accounts for combined forces acting there.

push rod lift

Valve lift

CASE 2 (similar explanaton of graph as in case 1)