MBD Simulation on IC Engine Valve Train
Aim:- Multibody Dynamics simulation on IC Engine Valve Train using Solidworks
Introduction and Theory:-
A Valve train is a mechanical system that controls operation of the intake and exhaust valves in an internal combustion engine. The intake valves control the flow of air/fuel mixture into the combustion chamber, while the exhaust valves control the flow of spent exhaust gasses out of the combustion chamber once combustion is completed.
The valve train consists of all the components responsible for transferring the rotational movement of the camshaft into the opening and closing of the intake and exhaust valves. Typical components are listed below in order from the crankshaft to the valves.
Camshaft:-
The timing and lift profile of the valve opening events are controlled by the camshaft, through use of a carefully shaped lobe on a rotating shaft. The camshaft is driven by the crank shaft and in the case of a four-stroke engine rotates at half the speed of the crankshaft.
Motion is transferred from the crankshaft to the camshaft most commonly by a rubber timing belt, a metallic timing chain or a set of gears.
Pushrod:-
Pushrods are long, slender metal rods that are used in overhead valve engines to transfer motion from the camshaft (located in the engine block) to the valves (located in the cylinder head). The bottom end of a pushrod is fitted with a lifter, upon which the camshaft makes contact. The camshaft lobe moves the lifter upwards, which moves the pushrod. The top end of the lifter pushes on the rocker arm, which opens the valve.
Rocker arm / bucket tappet:-
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. Overhead valve engines use rocker arms, which are actuated by a pushrod and pivot on a shaft or individual ball studs in order to actuate the valves.
Valves:-
Most modern engines use poppet valves type, although sleeve valves, slide valves and rotary valves have also been used at times. Poppet valves are typically opened by the camshaft lobe or rocker arm, and closed by a coiled spring called a valve spring.
Objectives:-
- To model the parts and assemble them in SolidWorks.
- To run the simulation using the below parameters or cases
|
Sl.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
Motion study setup:-
- First, we will understand the concept of the IC Engine Valve train
- Then, we will calculate the length (Distance between two centers) by using the cam lift formulae
CAM Lift = (L-R1)+R2
- In case 1:-
We will take R1=12.5mm and R2=5mm and given cam lift = 3.5mm then our Length will be 10.5mm
- In case 2:-
We will take R1=12.5mm and R2=5mm and given cam lift = 6mm then our Length will be 13.5mm
- Then, we will design the components required according to the required dimensions.
- Then, we will assemble them
- And, we will mate the components as required
- Then, we will add a spring between the Valve and Valve pin and we will provide a stiffness valve
- Then, we will add a motor and we will perform motion study with 1500rpm and we will set frames as 8000 (for better visualization of the plots)
- Then, we will give contact between the parts
- We will apply the entire material as Cast carbon steel (as mentioned)
- Then, we will obtain the contact forces
- Then, we will also obtain the valve lift
- And finally, we will observe the results obtained.
Part and Assembly Designs:-
Cam lift 3.5 mm
Cam lift with 6 mm
Push Rod
Rocker Arm
Valve
Valve Pin
IC Engine Valve Train with cam lift 3.5mm
IC Engine Valve Train with cam lift 6mm
Motion study on IC Engine Valve train with cam lift 3.5mm Animation video:-
Motion study on IC Engine Valve train with cam lift 6 mm Animation video:-
Plots in case1:-
Contact force between Cam and Pushrod
Contact force between Pushrod and Rockerarm
Contact force between Rockerarm and Valve
Contact force between Rockerarm and Valve in 'X' component
Linear Displacement of Valve lift
Plots in case2:-
Contact force between Cam and Pushrod
Contact force between Pushrod and Rockerarm
Contact force between Rockerarm and Valve
Contact force between Rockerarm and Valve in 'X' component
Linear Displacement of Valve lift
Google Drive link for CAD Files:-
https://drive.google.com/drive/folders/1Fn9yCmN8qtNG3RLxZsK3WUNxwnObBr1v?usp=sharing
Observation and Explanation of plots:-
So, If we observe the plots there is difference between the two cases and the plot with the contact force between the Rocker arm and valve varies while measuring with respect to the X direction and measuring with respect to magnitude because of the frictional force.
Conclusion:-
We have successfully completed the Multi Body Dynamics simulation on IC Engine Valve train using Solidworks and obtained the results.