IC Engine Valve Train mechanism using SolidWorks (Multibody Dynamics)

Aim:

To model and assemble the parts of an engine valve train using SolidWorks. Perform motion analysis on the system to determine important parameters like linear displacment of pushrod and contact forces between different components of the system.

Objective:

1. Create a 3D model of the cam (3.5mm camlift)
2. Create a 3D model of the cam (6mm camlift)
3. Create a 3D model of pushrod
4. Create a 3D model of rockerarm
5. Create a 3D model of valve
6. Create a 3D model of valve mount

Theory:

The valve train consists of the valves and a mechanism that opens and closes them. The opening and closing system is called a camshaft. The camshaft has lobes on it that move the valves up and down. Engine valve train generally consists of the following components

1. Cam
2. Pushrod
3. Rockerarm
4. Valve
5. Valve mount

The cam is rotated using power from engine crank via a timer belt. the rotory motion of cam is translated to the pushrod. pushrod reciprocates and transfers motion to rocker arm pivoted about a point. The rockerarm inturn opens the valve. valve is closed using a spring attatched to itself and a mount.

Model:

Cam:

Camlift = (L-R1) + R2

length between the two centers,L = 10mm

Radius of larger circle,R1 = 10mm

Radius of shorter circle,R2 = 3.5mm

(10 - 10) + 3.5 = 3.5.

Camlift = (L-R1) + R2

length between the two centers,L = 13mm

Radius of larger circle,R1 = 13mm

Radius of shorter circle,R2 = 6mm

(13 - 13) + 6 = 6.

Pushrod:

Rockerarm:

Valve:

Valve mount:

Assembly:

camlift 3.5mm

Camlift 6mm:

Plots:

3.5mm camlift

linear displacment of pushrod

Contact force between cam and pushrod

Contact force between pushrod and rockerarm

Contact force between rockerarm and valve

6mm camlift

linear displacment of pushrod

Contact force between cam and pushrod

Contact force between pushrod and rockerarm

Contact force between rockerarm and valve

Contact force between rocker arm and valve along X direction alone

For 3.5mm camlift

For 6mm camlift

Variation in contact force when for along x direction and magnitude is because the force applied by rocker arm on the valve is acting along both the x and y direction.

hence when we clculate the force along x direction we get only the cosine component of the actual force, while the sine component contains the force along y direction.

as the magnitude of the components vary for different angle of rocker arm the values of force along x direction also varies.

Conclusion:

The engine valve train components are modelled and assembled in SolidWorks. Motion analysis is done to the system and required physical parameters are found and compared for different camlift heights.