MBD Simulation on IC Engine Valve Train

AIM:-To create 3-D model of various components of IC engine valve train and perform motion analysis on the IC engine valve train for various camlift .

THEORY AND PRINCIPLE:-Engine valves are used in engines to allow air -fuel /air to enter into cyclinder and to push exhaust gases from cylinder at specific time during the engine cycle.The valve mechanism consists of cam, pushrod,rocker arm,valve seat,valve stem.All the components are assembled together to get desired motion .The input to the mechanism is given by the engine through some chain drives.The mechanism are almost found in all automobiles.In this mechanism rotaory motion of the cam is converted into linear motion of the valve stem with help of the rocker arm, push rod.Cam and follower mechanism is used in this mechanism to actuate the valves accordingly with the suction and exhaust strokes.The cam and follwer mechanism is used in metal cutting machines ,in machines used in food industry.Different typre of displacements of the push rod /follower is obtained by setting the offset distance if desired.

GOVERING EQUATIONS:-

`CL=(L-R1)+R2`

where CL= cam lift

L=distance between centres.

R1=radius of lower circle.

R2=radius of upper circle.

OBJECTIVES OF THE PROJECT:-

1. Valve Lift.
2. The contact force between
   • Cam and Push Rod
   • Pushrod and Rocker Arm
   • Rocker Arm and Valve
3. Perform motion analysis ,create part modelling and assemble them.

BODY OF THE CONTENT:-

CREATING 3-D MODEL OF THE CAM:-

1. Select the front plane and draw a circle of given diameter with centre as origin ,and other circle vertical in relation with the previously drawn circle and provide distance between there centres.
2. Now draw two lines which are tangent to both the circles .
3. Now trim the excess sketch to get desired shape of cam and exit the sketch.

Now extrude the sketch from midplane 5mm on either sides the plane.

CREATING 3-D MODEL OF THE PUSHROD:-

1. Select the front plane make a sketch with 3 lines perpendicular lines each of different dimensions and the close the figure with 3 point arc and exit the sketch.
2. Making the longest line as refrence from the sketch and use revolve command to crate pushrod.

CREATING ROCKER ARM:-

1. Select the front plane and sketch the rocker with help of 3 point arc and line command.
2. After completing the sketch use fillet at sharp edges and make them curvy in nature.
3. After sketching exit it and extude it from midplane 10mm on either sides.
4. This results in rockerarm 3-D model.

CREATING VALVE MOUNT:-

1. Select the front plne and create an L-shape sketch at a certain distance from the origin, exit the sketch.
2. Now make the line adjacent to the origin as reference and use revolve command to create 3-D mofel of valve mount.

CREATING THE VALVE:-

1. Select the front plane and make sketch of the valve with 3 point arc and line command,exit the sketch.
2. Make the line passing through origin as reference and use revolve command to create 3-D model of the valve.

ASSEMBLY OF THE VALVE MECHANISM:-

1. Choose assembly model and insert all the components one at a time or individually for constraining them.
2. After inserting the part model one by one make them constrain using mate option so that when all the components are assemble desired output is obtained.
3. Following mates were given to constrain valve mechanism.
4. Using physical dynamics command to ensure that all components are in contact before performing motion analysis.

MOTION ANALYSIS OF THE VALVE MECHANISM:-

1. Select SOLIDWORKS Motion from the top ribbon.
2. Now click on motion study at the bottom the solidworks desktop so that motion analysis can be started.
3. Now assign motor to cam by selecting the motor and assiging at the axis of the cam.
4. Now use solod contact command to ensure that there is contact between the components so that while motion analysis they perform well.
5. Insert spring between valve seat and valve so that the valve returns to its original postion after moving forward.
6. Now setting frames/sec as 200 to capture frames of angle of cam and obtain plots.
7. Now using plots and results select the component whose forces ,angular dispalcement,velocity,acceleration.linear displacement,velocity,acceleration has to plotted with time.

CALCULATIONS:-

PLOTS:-

Plots for camlift =3.5mm

PLOT for camlift=6mm

INFERENCES FROM THE PLOT:-

1. We can observe that as camlift increases the valve lift also increases.
2. The rocker arm magnifies the inout force fron cam to valve lift.
3. We can observe that in contact force between rockerarm and valve is both positive and negative when measured along x-direction because the valve moves to and fro in x-diection.while the same kind of motion is obtained when contact force between rockerarm and valve is measured but in this case we only measure the magnitude,we are not concerned about the direction in both the cases when cam lift =3.5mm,6mm.
4. Reaction forces increases for all components when cam lift is increased.
5. When cam lift is increased the valve opens and lets in air to enter more into combustion chamber,while its opposite when camlift is decreased.

CONCLUSION:-

1. Created 3-D models of all components.
2. Assembled all the components.
3. Performed the motion analysis.
4. Obtained plots like contact forces ,linear displacements.
5. Exported the results to EXCEL sheets.