MBD Simulation on IC Engine Valve Train

Aim: Tio perform MBD on an IC Engine Valve Train using SolidWorks

Introduction: The valve train refers to the assembly of components designed to open and close the intake and exhaust valves. Most new engines have overhead cam assemblies like the one shown. Other designs locate the camshaft lower in the engine and use push rods to move valve assemblies. The camshaft is rotated by a timing belt, timing chain or direct gear.

Cam

Rocker arm

Pushrod

Valve

Valve mount

For our valve train, the next step is to assemble all the parts. All the parts are inserted into the assembly and provided constraints such that all the parts have one degree of freedom.

For this, axes of different parts and planes of the assembly as constrained so that the parts can move as we desire them to.

Motion Study Analysis

We take 9000 frames per second as 1500 rpm translates to 9000 degrees/sec.

Spring length = 45mm, Spring constant(k) = 10N/mm

For Case 1

Cam lift = 3.5mm

R1 = 10mm

R2 = 17.5mm

Using the formula for cam lift = L - (R1+R2)

Hence, L = 11mm.

The plots obtained after designing the cam according to the above-given dimensions are shown below.

For Case 2

Cam lift = 6mm

R1 = 10mm

R2 = 17.5mm

Using the formula for cam lift = L - (R1+R2)

Hence, L = 13.5mm.

The plots obtained after designing the cam according to the above-given dimensions are shown below.

Plots Explanation:

CASE 1 - Maximum value of lift is seen to be 57mm according to the plot.

The contact force between the pushrod and cam comes to be 5500N to 7383N.

The contact force between pushrod and rocker arm comes to be 5924N.

The contact force between rocker arm and vale comes to be 1223N to 1631N.

CASE 2 - Maximum value of lift is seen to be 62mm according to the plot.

The contact force between the pushrod and cam comes to be 3833N.

The contact force between pushrod and rocker arm comes to be 3629N to 4838N.

The contact force between the rocker arm and vale comes to be 350 to 700N.