IC Engine Valve Train

A valve train is a mechanical system that controls intake and exhaust valve operation within 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 exhaust gasses spent out of the combustion chamber once combustion is complete. A lifter is mounted at the bottom end of a pushrod, on which the camshaft makes contact. The lobe of the camshaft moves up the lifter which raises the pushrod. The lifter's top end falls into the rocker neck, releasing the door.

Contact force: If an object is in contact with some other entity a contact force occurs. If there are two bodies in contact with one another, there are reciprocal interaction forces that fulfill Newton's Third Law of Motion.

Magnitude: When two bodies are held in contact, electromagnetic forces at the surfaces of the bodies work between the charged particles. In this way, each body exerts the other's contact force. The magnitudes of the contact forces acting on the two bodies are equal but their movements are opposite and thus Newton's third law is faithful to the contact forces.

X-Direction: The contact force which is along X-axis alone(both +ve & -ve)

Calculation:

CAM Lift (CL)= (L-R1)+R2

case1: CL=(12.5-12.5)+3.5

Diameter 1 = 25mm

Diameter 2 = 7mm

Centre Distance=12.5mm

case2: CL=(12.5-12.5)+6

Diameter 1 = 25mm

Diameter 2 = 12mm

Centre Distance = 12.5mm

PROCEDURE FOR DOING IC Engine Valve Train MOTION STUDY IN SOLID WORKS

Step 1: Creating the cad model.

Step 2: Create new assembly select the parts

CONSTRAINTS:

1. Coincide1-rocker arm and Right plane
2. Coincide2-rocker arm and Top Plane
3. Coincide3-rocker arm front plane and Front Plane
4. Coincide4-push rod axis and front plane
5. Coinside5-cam front plane and front plane
6. Coinside6-valve stem axis and front plane
7. Coinside7-valve stem axis and valve axis
8. Distance mate 1 - right plane of both rocker arm and push rod
9. Distance mate 2 - right plane of both rocker arm and cam
10. Distance mate 2 - right plane of both rocker arm and valve stem
11. Distance mate 3 - top plane of rocker arm and cam
12. Distance mate 4 - top plane of rocker arm and valve stem

Now the assembly is ready

Step 3: Click on assembly at the tools and select rotate component (In move component session). On selecting the part and move the one component which makes relative motion between parts and this gives the each component to touch each other.

Step 4: Click the SOLIDWORKS add-in and enable motion study.

Step 5: Now create the new motion study and change animation to motion analysis.

Step 6: Select the motor option to give the torque to the driving wheel (we can give the rpm, time)

Step 7: Select the contact option to give the materials (we can assign material here). For changing other material follow the steps as follows select every component-right click by preesing the control-material-edit material-select the material which we needed.

Step 8: Now we can use calculate options to calculate the results.

Step 9: Now we can plot the graph using plot option. To save in excel (Right click the plot and click the save as CSV option).

Step 10: For getting precise click on settings and we can enable precise contact and no of frames.

Step 11: Now we can plot the graph using plot option.

Step 12: We can save the results.

RESULT PLOTS:

CASE 1:

CASE2:

CONCLUSION:

Sl.No	CAM Lift (mm)	Speed (RPM)	Material	Displacement of Valve(mm)	Contact force between rocker arm and valve -magnitude (N) Peak	Contact force between rocker arm and valve -X Direction (N) Peak	Remarks
1	3.5	1500	Cast Carbon Steel	52.1	2250 TO 3567	-650 TO -866	displacement of 52.1mm with 3567N magnitude and -866N at x-axis only
2	6	1500	Cast Carbon Steel	54	2500 TO 3000	-600 TO -790	displacement of 54mm with 3500N magnitude and -790N at x-axis only

Due to the absence of a damper, the contact force varies at a regular interval between each body of contact. The plot implies there is the frequent displacement of the valve but there is micron level variation up to 100microns and the contact force varies based on solid contact of two bodies.
While measuring magnitude which gives a summation of all the forces in 3 axes and while measuring in x-direction implies at the contact of the body the forces obtained in x-axis alone. From the obtained results we can conclude that the contact force between each body can be found and displacement of the valve. Based on the requirement we can change the dimension to the requirements.