MBD Simulation on IC Engine Valve Train

1) INTRODUCTION:-

A Valvetrain is a mechanical system that controls the 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 combustion chamber once combustion is completed.

2 ) OBJECTIVE:

• To run the simulation using the below parameters:-

S. NO.	Cam Lift(mm)	Speed(RPM)	Material
1.	3.5	1500	Cast Carbon Steel
2.	6	1500	Cast Carbon Steel

To Obtain the:-

• Valve Lift & the contact force between:

• Cam and Push Rod

• Pushrod and Rocker Arm

• Rocker Arm and Valve

The contact force between the Rocker arm and valve with respect to the X-direction and measuring with respect to magnitude.

3) CAM LIFT FORMULA:

CAM Lift can be derived from the sketch

• The diameter of the lower circle (D1)- 35 mm
• The diameter of the upper circle (D2)- 20 mm
• The distance between two centers (L)- 30 mm

4) PROCEDURE:

CAM- a cam is a rotating or sliding piece in a mechanical linkage used especially in transforming rotary motion into linear motion. It is often a part of a rotating wheel (e.g. an eccentric wheel) or shaft (e.g. a cylinder with an irregular shape) that strikes a lever at one or more points on its circular path.

The designed based on the lift specified and the dimensions are given

PUSHROD -Pushrods are long, slender metal rods that are used in overhead valve engines to transfer motion from the camshaft to the valve.

ROCKER ARM -Depending on the design used, the valves are actuated by a rocker arm, finger, or bucket tappet. Overhead camshaft engines use fingers or bucket tappets, upon which the cam lobes contact.

VALVE -Most modern engines use poppet valves type, although sleeve valves, slide valves, and rotary valves have also been used at times.

VALVE MOUNT – The Valve Stem is designed with shaft hole size equal to the valve width, so that valve can move up and down with respect to its axis.

ASSEMBLY -

5)PLOTS –

• CASE 1:

Valve Lift VS Time => The valve lift is due to the variation in the rocker arm movement with respect to the cam movement

Contact force (cam & pushrod) VS time => This plot gives the contact force between the cam and pushrod due to the cam movement. the peak value is due to the contact of end portion of the cam with the pushrod.

Contact force (pushrod &rocker arm) VS time => This graph shows similarity to the previous graph, thereby resembling the uniform transfer of motion.

Contact Force (Rocker Arm & Valve) VS Time => The graph intends to represent the downward force that the Rocker Arm exerts on the Valve.

Contact Force (Rocker Arm & Valve) VS Time - X DIRECTION => The plot works as a comparison between the Contact Force measured as Magnitude or in the X Direction.

• CASE-2 –

Valve Lift VS Time=>

Contact Force (Cam & Pushrod) VS Time=>

Contact Force (Pushrod & Rocker Arm) VS Time=>

Contact Force (Rocker Arm & Valve) VS Time =>

Contact Force (Rocker Arm & Valve) VS Time - X DIRECTION

6) CONCLUSION;

The contact force between the components taken with respect to the magnitude gives the positive values due to the TO and FRO motion of parts that don't take the axes as the main criteria.

but in case of contact force between the valve and rocker arm (x-component), the values are plotted with respect to the x-axis and so the negative values are obtained.

The Motion Analysis gives a satisfactory idea about the functioning of the IC Engine Valve Train wherein further scope of improvements exist to make it more smooth and efficient.

7)ANIMATION VIDEO;

CASE-1:https://youtu.be/7gJm32RnhNk

CASE-2:https://youtu.be/jy5fLe8l598

8)GOOGLE DRIVE LINK-PART & ASSEMBLY FILE:

https://drive.google.com/drive/folders/1gnXK2ahU71PaqLoO2gnBwmMhHjbwrG2L?usp=sharing