MBD Simulation on IC Engine Valve Train

Project:- MBD Simulation on IC Engine Valvetrain

Challenges:- to design 3.5mm and 6mm cam profile and study the cam lift phenomenon with contact force between moving parts and contact force of rocker arm and valve in the x-direction and explain

Procedure

• Measure cam lift and design cam profile for precise motion
• Design specific parts in the separate part file (cam, push rod, rocker arm, valve, valve seat )
• Assemble all the parts with precise distance to obtain required motion
• Constrain all the parts with physical contact with each other and give motion without any loss of power
• Check all parts in an assembly are constrained and have precise motion of parts as they make contact
• Giving material property to each part (material: cast carbon steel)
• To resist and to retract valve in its original position addition of spring between the valve and valve mount with free length 45mm and stiffness 10 N /mm
• Providing 1200 frame rate to measure the accurate motion of valve train
• After motion analysis obtaining graph for the study of MBD simulation on IC Engine valve train
• Graphs obtained are as follows (different for both 3.5mm and 6mm cam profile)

1. Valve displacement
2. The contact force between cam and push rod
3. The contact force between the push rod and rocker arm
4. The contact force between rocker arm and valve
5. The contact force between valve and rocker arm in the x-direction

Explanation

The standard formula was given to measure the cam lift to obtain precise lift

CAM Lift Formula

CAM Lift can be derived from the sketch

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

CAM Lift = (L-R1)+R2

Giving perfect constrained motion to obtain and to avoid free movement of the body

To obtain rotation motion of cam in IC Engine valve train motion specifying the axis of rotation of cam with 1500 rpm

Cam3.5mm

CAM Lift Formula ( for 3.5mm cam)

CAM Lift can be derived from the sketch

• The diameter of the lower circle (D1)- 20mm
• The diameter of the upper circle (D2)- 7 mm
• The distance between two centers (L)- 10 mm

CAM Lift = (L-R1)+R2 =(10-10)+3.5=3.5

Pushrod

Rocker arm

Valve

Valve mount

assembly

working of the valve train

3.5 mm cam lift

3.5 MM CAM LIFT GRAPH

6 mm cam lift study

VALVE & ROCKER ARM CONTACT FORCE IN X- DIRECTION

conclusion & explanation of the result

The contact force graph between the valve and rocker arm in direction x shows the movement of rocker arm and valve on a line contact

In line contact between the valve and the rocker arm are due to the action of force applied by spring which opposes the rocker arm movement means resist to move the valve in a downward direction

Due to the resistance of movement of valve offered by the spring to the valve tends to push back valve in the original position

The resistance to movement of the valve the graph of contact force shows the negative force on the rocker arm, As well as the force in the x-direction of between the rocker arm and valve, changes the position along the surface of the valve in the x-direction

As the graph shows the negative force are due to the movement of the point contact of the rocker arm to valve arm changes the point of contact.

That’s why the graph shows the negative direction of the force.

zip file

https://drive.google.com/open?id=1NiPBWwkmKJwzhM1luQtK7PW5CKdbZ-Zb