Motion analysis of a IC Engine Valve Train
Aim:-
To run an MBD simulation on IC Engine Valve Train and obtain a few plots.
Theory:-
The IC Engine valve train is a mechanical system that controls the opening and closing of the intake and exhaust ports. Its one of the vital components of an engine and its functioning is very crucial for the engine to work properly.
The valve train mainly consists of a Camshaft, a Cam, pushrod, Rocker arm, valve, valve spring and valve guide. These components altogether transform the rotational motion of the cam shaft to linear oscillatory motion of the Valve.
Procedure:-
First all the components were designed according to the given dimensions and then assembled accordingly to resemble an accurate IC Engine Valve train. The assembly is given below:-
After the assembly was complete, a motion study was setup.
Parameters for the Motion Analysis:-
1. Rotational motor at cam at 1500RPM.
2. A valve spring of 45mm length and 10N/mm stiffness is attached.
3. Contact forces between all the components are given.
4. All components are given Cast Carbon Steel as material.
5. The motion analysis is set at 9000 Frames/sec.
6. The analysis is carried out for 0.2 sec.
Observations:-
The following graphs were plotted after the motion analysis was complete:-
1. Valve Lift
2. Contact Force between Cam and Pushrod
3. Contact Force between Rocker Arm and Pushrod
4. Contact Force between Rocker Arm and Valve
5. Contact Force between Rocker Arm and Valve (X-Direction)
Results:-
1. the maximum valve lift for this setup is 55mm
2. Maximum contact Force between,
a. Cam and Pushrod = 10,230N
b. Pushrod and Rocker Arm = 10357N
c. Rocker Arm and Valve = 1990 N
Conclusion:-
1. The displacement of the valve lift can be adjusted by the cam profile and cam lift value.
2. The contact forces are quite high for this setup.
3. The CF value between the rocker arm and the valve in terms of magnitude and X-direction varies, this is because, the rocker arm moves in both positive and negative x-axis w.r.t the valve. The x-component is only a measure of the frictional force between the rocker arm and the valve.