MBD Simulation on IC Engine Valve Train

AIM:

Design and motion analysis of 'IC ENGINE VALVE TRAIN' using solidworks.

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 (or air alone for direct-injected engines) into the combustion chamber, while the exhaust valves control the flow of spent exhaust gasses out of the combustion chamber once combustion is completed.

CAM: The cam can be seen as a device that converts rotational motion to reciprocating (or sometimes oscillating) motion.A common example is the camshaft of an automobile, which takes the rotary motion of the engine and converts it into the reciprocating motion necessary to operate the intake and exhaust valves of the cylinders.

PUSH ROD: It is a rod actuated by a cam to open or close a valve of an internal combustion engine.

ROCKER ARM: Rocker Arms are typically in between the pushrod and the intake and exhaust valves. They allow the pushrods to push up on the rocker arms and therefore push down on the valves.

VALVE: Valve is a device to close and open a passage. In motor vehicle engines, two engine valves are used for each cylinder-an inlet (or intake) valve and an exhaust valve.

OBJECTIVES:

The main objective of the project are:

1)To make 3-D cad models of all the components of valve train and make their assembly.

2)To perform motion analysis of the valve train mechanism.

3)To obtain the following plots:

• Valve Lift.
• The contact force between Cam and Push Rod.
• The contact force between Push rod and Rocker Arm.
• The contact force between Rocker Arm and Valve.

GIVEN:

SR.No	CAM Lift (mm)	Speed (RPM)	Material
1	3.5	1500	Cast Carbon Steel
2	6	1500	Cast Carbon Steel

The formula for cam lift is given as:

CALCULATIONS:

By using the above given formula we can find the dimensions for both the cases of our cams

CASE 1: CAM LIFT = 3.5MM : D1 = 25MM : D2 = 10MM

CAM LIFT = (L - R1) + R2

3.5 = (L - 12.5) + 5

L = 11MM

CASE 2: CAM LIFT = 6MM : D1 = 25MM : D2 = 10MM

CAM LIFT = (L - R1) + R2

6 = (L - 12.5) + 5

L = 13.5MM

PROCEDURE:

1)Initially we make 2-D drawings of all the components as per the mentioned dimensions.After that we convert all 2-D drawings to 3-D cad models by using extrude boss-base command.The screenshot of isometric view of all the cad models are shown below:

Isometric view of 3-D CAD MODEL of CAM:

Isometric view of 3-D CAD MODEL of PUSH ROD:

Isometric view of 3-D CAD MODEL of ROCKER ARM:

Isometric view of 3-D CAD MODEL of VALVE:

Isometric view of 3-D CAD MODEL of VALVE STEM:

2)After finishing with all the 3-D cad models of components we open assembly and insert all the componets in the assemby file one by one.The isometric view of 3-D cad model of assembly of ic engine valve train is shown below:

Isometric view of assembly of IC ENGINE VALVE TRAIN:

3)After finishing with assembly we do the motion study analysis for the ic engine valve train assembly.

MOTION STUDY ANALYSIS:

1. First select solidworks motion from solidworks add-ins.Then click on motion analysis from the drop down list at the left bottom corner.
2. After that apply motor of 1500 rpm to the cam axis.
3. Then apply contacts between cam and push rod,push rod and rocker arm,rocker arm and valve.
4. After that apply spring between the top edge of valve stem and bottom edge of valve of length of 45 mm which is pretensioned by 10 mm and having spring constant of 10N/mm.
5. After this click on motion study properties and put frames per second as 9000 and click on precise contact.
6. After that click on calculate and wait till the animation finishes.
7. Then click on results and plot and obtain the desired plots.
8. At last we click on save animation and obtain the animation of our mechanism.
9. The output plots of both the cases are shown below.

CASE:1 - CAM LIFT OF 3.5MM

OUTPUT PLOT:

1)Valve lift:

2)Contact force between cam and push rod:

3)Contact force between push rod and rocker arm:

4)Contact force between rocker arm and valve(Magnitude):

5)Contact force between rocker arm and valve(X-Component):

The animation link of case 1 is given below:

https://youtu.be/w5dHAc1qa5s

CASE:2 - CAM LIFT OF 6MM

OUTPUT PLOT:

1)Valve lift:

2)Contact force between cam and push rod:

3)Contact force between push rod and rocker arm:

4)Contact force between rocker arm and valve(Magnitude):

5)Contact force between rocker arm and valve(X-Component):

The animation link of case 2 is given below:

https://youtu.be/IxpBDj_PKVo

CONCLUSION:

1. Thus we have made 3-D cad models of all the components and also their assembly was done.Also we have done the motion analysis of valve tarin and their various graphs were also plotted.
2. From above plots of linear displacement of valve we can conclude that valvelift increases as we increase the cam lift so they both are directly proportioal to each other.
3. Also contact forces between the components increases on increasing the cam lift as they store more potential energy.
4. The contact force value between rocker arm and valve in x direction shows us the negative value while when the whole magnitude is plotted it shows us the positive value this is because the motion of valve train is in y direction so in x direction only friction force is acting which is very less as compared to others so we are getting a negative plot and the plot of magnitude is resultant of forces in all the direction so we get positive values.

REFERENCES:

https://www.speedwaymotors.com/the-toolbox/camshaft-specifications-and-terminology/28647

http://engineering.myindialist.com/2013/introduction-of-cams-and-types-of-cam-and-followers/#.XuygYmgzYdW

LINK FOR SOLIDWORKS PARTS AND ASSEMBLY FILE IS GIVEN BELOW:

https://drive.google.com/drive/folders/1Wixb9CavgmkW9s2_L6GJcHTMLj4SA51m?usp=sharing