MBD Simulation on IC Engine Valve Train Using SolidWorks
Aim:
To the model parts of IC Engine Valve Train assembly and to perform Multibody Dynamics Simulation using solidworks on the IC Engine Valve Train assembly under two different Cam lift conditions.
Objective:
- To model parts of the IC Engine Valve Train.
- Then to assemble the IC Engine Valve Train Assembly with proper constraints.
- To perform motion analysis with two different cam lift conditions and to get plots of linear displacement and contact forces between several parts.
- Finally to analyze the resulting plots.
Theory:
A valvetrain or valve train is a mechanical system that controls operation of the intake and exhaust valves in an internal combustion engine.The valve train of an internal combustion engine includes components required to control the flow of gases into and out of the combustion chamber. This includes valves and related components required to allow the air-fuel mixture to enter the combustion chamber, seal the combustion chamber during compression and combustion, and evacuate exhaust gases when combustion is complete. The type of valve train used for a reciprocating engine depends on the engine design and whether the engine is a four-stroke cycle or two-stroke cycle unit.
Valves allow the flow of air-fuel mixture into the cylinder, and the flow of exhaust gases from the cylinder. Most exhaust valves used in Briggs & Stratton engines are made from austenitic steel. Austenitic steel is a heat-resistive metal alloy containing of cobalt, tungsten, and chromium. and has properties similar to stainless steel. Stainless steel is a ferrous alloy alloyed with consisting of chromium or nickel. Austenitic steel used for valves offers similar heat and corrosion resistance at a lower cost than stainless steel.
The IC Engine Valve Train Assembly comprises of the following parts:
1. Cam
2. Push Rod
3. Rocker Arm
4. Valve
5. Valve Mount
Software Used:
Solidworks
Procedure & Outputs:
As per the dimensions provided in the video the parts of IC Engine Valve Train are drawn as follows,
1.Cam Lift Conditions:
2.Formula:
For sketching the cam for different lifts the following formula was used,
Case 1: Cam lift(3.5 mm)
R1= 17.5mm
R2= 10mm
3.5=(L1−17.5)+10
L =11mm
Case 2: Cam lift(6 mm)
R1= 17.5mm
R2= 10mm
6=(L2−17.5)+10
L=13.5mm
3.Parts:
3.1.Cam:
To create it, Extrude and several other 2D sketch tool(line,circle,trim,etc) commands are used.
3.2.Push Rod:
To create it, Revolve and several other 2D sketch tool(line,arc) commands are used.
3.3.Rocker Arm:
To create it, Extrude,Fillet and several other 2D sketch tool(circle,line,arc,trim,etc) commands are used.
3.4.Valve:
To create it, Revolve,Fillet and several other 2D sketch tool(arc,line, ,etc) commands are used.
3.5.Valve Mount:
To create it Revolve and several other 2D sketch tool(line,etc) commands are used.
3.6.Assembly:
To assemble the components each parts are brought one by one into the assembly window and constrained properly using the proper mate and coincident constraint options to achieve the desired motion.
4.Motion Analysis:
The Motion Analysis for the two different Cam lift conditions are as follows,
4.1.Case 1: Cam lift(3.5 mm):
After successful assembly, Solidworks motion is selected from Solidworks add-ins and motion study is made active. For this case(Case 1), a motor speed of 1500 rpm is provided to the cam axis.
Then the cam created for the Cam lift of 3.5 mm is used in this case. Solid contact between cam and pushrod, pushrod and rocker arm, rocker arm and valve were given and material provided was Steel(dry).
A linear spring was provided between upper edge of valve mount and lower stem of valve with the spring pretensioned to it's natural length to 45 mm.
Finally the following plots are created and the datas are exported to a Excel file and the plots are made in the Excel document for each case.
4.1.1.Valve Lift
The valve lift during motion was exported to excel document and the plots are made for those data exported.From the plot the maximum position of valve was little above 5.2000E+01 (52.218 mm) while minimum position was little below 5.0000E+01 (50.077 mm). Hence valve lift can be calculated as the difference between these two positions and was found to be 2.141 mm.
4.1.2.contact force between Cam and Push Rod
From the plot of contact force between cam and push rod, initially the force was too high and was due to jerk and sudden contact of the two parts in the system. After this the force varies with gradual ups and downs with a maximum value between 1.0000E+03 N to 1.5000E+03 N.
4.1.3.contact force between Pushrod and Rocker Arm
Similarly from the plots of contact force between Rocker arm and Pushrod, initially the force was too high and was due to sudden contact and jerk of the system. After this the force varies with gradual ups and downs with a maximum value between 1.0000E+03 N to 1.5000E+03 N.
4.1.4.contact force between Rocker Arm and Valve
From the plot of contact force between Rocker arm and Valve, initially the force was too high and was due to jerk and sudden contact of the two parts in the system. After this the force varies with gradual ups and downs with a maximum value between 2.0000E+02 N to 3.5000E+02 N.
4.1.5.Video link
https://youtu.be/UKk6MMsR_yY
4.2.Case 2: Cam lift(6 mm):
After successful assembly, Solidworks motion is selected from Solidworks add-ins and motion study is made active. For this case(Case 2), a motor speed of 1500 rpm is provided to the cam axis.
Then the cam created for the Cam lift of 6 mm is used in this case. Solid contact between cam and pushrod, pushrod and rocker arm, rocker arm and valve were given and material provided was Steel(dry).
A linear spring was provided between upper edge of valve mount and lower stem of valve with the spring pretensioned to it's natural length to 45 mm.
Finally the following plots are created and the datas are exported to a Excel file and the plots are made in the Excel document for each case.
4.2.1.Valve Lift
The valve lift during motion was exported to excel document and the plots are made for those data exported.From the plot the maximum position of valve was above 5.3500E+01 (53.815 mm) while minimum position was little below 5.0000E+01 (50.077 mm). Hence valve lift can be calculated as the difference between these two positions and was found to be 3.738 mm.
4.2.2.contact force between Cam and Push Rod
From the plot of contact force between cam and push rod, initially the force was too high and was due to jerk and sudden contact of the two parts in the system. After this the force varies with gradual ups and downs with a maximum value between 2.0000E+03 N to 3.5000E+03 N.
4.2.3.contact force between Pushrod and Rocker Arm
Similarly from the plots of contact force between Rocker arm and Pushrod, initially the force was too high and was due to sudden contact and jerk of the system. After this the force varies with gradual ups and downs with a maximum value between 2.0000E+03 N to 4.0000E+03 N.
4.2.4.contact force between Rocker Arm and Valve
From the plot of contact force between Rocker arm and Valve, initially the force was too high and was due to jerk and sudden contact of the two parts in the system. After this the force varies with gradual ups and downs with a maximum value between 4.0000E+02 N to 8.0000E+02 N.
4.2.5.Video link
4.3 Explain why the contact force between the Rocker arm and valve varies while measuring with respect to the X direction and measuring with respect to magnitude:
In this entire simulation the Contact Force between Rocker Arm and Valve varies while measuring with respect to the X Direction and measuring with respect to Magnitude as the result in case of X Direction depicts Negative Values due to Frictional Contact. But while measuring and plotting the Magnitude of Contact Force, the direction is not kept in mind and the Contact Line performs a "to and fro" motion in vertical direction which neglects the need for measuring the direction. Hence, output comes out to be Positive value.
Case 1: Cam lift(3.5 mm):
1.W.r.t Magnitude
2.W.r.t to X axis
Case 2: Cam lift(6 mm):
1.W.r.t Magnitude
2.W.r.t to X axis
Parts and Assembly :
https://drive.google.com/file/d/113wQS2FNu73VtN4RXR2zKtfZLhL-8--y/view?usp=sharing
(The Parts and assembly files are put into Single zip file)
References:
1.https://en.wikipedia.org/wiki/Valvetrain
2.http://courses.washington.edu/engr100/Section_Wei/engine/UofWindsorManual/Valve%20Train.htm
Conclusion:
Thus finally the simulation was created successfully.The desired results and plots were created and clearly explained.