IC engine valve train mechanism
IC engine valve train mechanism
introduction:
This assignment is about designing a valve train and simulating it for different cam lifts and observing the changes that has been made during the working.this simulation helps us to get in depth understanding of parameters like the lift of the cam make changes.with this we can make different sort of cam mechanisms and study the working of each and every cam.we used to make cam lift plots with great difficulty in the exams but with the help of this tool any parameters can be found out easily.
Procedure:
the assignment started with the designing of the solid models of the parts to be used in the valve train mechanism.then the assembly where the degree of freedom of each and every component is fixed so that the component moves in a desired way.the motion study is been conducted on this mechanism with different cam size are used and a motor is connected to cam and spring at valve mount to retain the initial position of the valve, then motion simulation is executed
since my desktop quiet slow i simulated it in 60fps
result:
valve lift & contact force between push rod and rocker arm:
cam lift -3.5mm
cam lift-6mm
the angular velocity of the cam is also cyclical. Due to that linear displacement of valve is cyclic in nature
the contact force looks the same as well
angular displacement of cam and contact force between cam and pushrod:
cam lift-3.5mm
cam lift-6mm
the angular displacement in the starting seems to be fluctuating because it has not gained the moment to rotate at a constant speed and due to the reaction force fluctuation but as the cam rotates it gains moment and start it rotate at a constant speed with minimum fluctuation
contact force reaches peak when the spring is compressed or when cam lobe reaches its peak
rocker arm & valve and rocker arm & valve x_direction:
cam lift-3.5mm
cam lift-6mm
As expected the contact force fluctuates as the cam lobe rotates ,but in case of measuring it with the x-axis direction it varies because, the magnitude force is taken as a resultant of all the force components of three axes, the x-component force tries the to push the valve left and right but the valve mount holds it in place.
model pic: