MBD Simulation on IC Engine Valve Train

Aim :- To model the parts for IC Engine Valve Train and to assemble them in solidworks and obtain the mbd simulation for it

Objective :-

• To model the parts for IC Engine Valve Train
• To assemble all the parts and to run the motion analysis for it
• To Obtain the simulation for the two diffrent parameters specified in the challange
• To plot the graph for the valve lift
• To plot the graph for the contact forces betn ,Cam and Push Rod,Pushrod and Rocker Arm,Rocker Arm and Valve

Formula / Governing Eqn :-

• Condition to run the simulation using the below parameters

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

• The Cam lift Formula can be derived as,

CAM Lift = ( L – R1 ) + R2

Where, L = Distance betn the two centre

R1 = Radius of Lower circle

R2 = Radius of Upper circle

• Now for the given parameters we have the values for the CAM Lift and considering the values for the (R1) & (R2) from the video so by using these values the unknown value of (L) can be found out

• Considering the dimensions from the Video,

  Let , D1 = 25mm so R1 = 12.5mm & D2 = 10mm so R2 = 5mm ,Cam lift = 3.5mm , L = ?

  Using the formula, Cam lift = ( L – R1 ) + R2

  3.5 = ( L – 12.5 ) + 5

  3.5 – 5 = ( L – 12.5 )

  - 1.5 = ( L – 12.5 )

  - 1.5 + 12.5 = L

  Therefore L = 11 mm

• D1 = 25mm so R1 = 12.5mm & D2 = 10mm so R2 = 5mm, Cam lift = 6mm , L = ?

Using the formula, Cam lift = ( L – R1 ) + R2

6 = ( L – 12.5 ) + 5

6 – 5 = ( L – 12.5 )

1 = ( L – 12.5 )

1 + 12.5 = L

Therefore L = 13.5 mm

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 combusion chamber once combustion is completed.

Components :-

The valve train consists of all the components responsible for transferring the rotational movement of the camshaft into the opening and closing of the intake and exhaust valves. Typical components are listed below in order from the crankshaft to the valves.

• Camshaft

The timing and lift profile of the valve opening events are controlled by the camshaft, through use of a carefully shaped lobe on a rotating shaft. The camshaft is driven by the crankshaft and— in the case of a four-stroke engine— rotates at half the speed of the crankshaft.

Motion is transferred from the crankshaft to the camshaft most commonly by a rubber timing belt, a metallic timing chain or a set of gears.

• Pushrod

Pushrods are long, slender metal rods that are used in overhead valve engines to transfer motion from the camshaft (located in the engine block) to the valves (located in the cylinder head). The bottom end of a pushrod is fitted with a lifter, upon which the camshaft makes contact. The camshaft lobe moves the lifter upwards, which moves the pushrod. The top end of the lifter pushes on the rocker arm, which opens the valve.

• Rocker arm / bucket tappet

Depending on the design used, the valves are actuated by a rocker arm, finger or bucket tappet. Overhead camshaft engines use fingers or bucket tappets, upon which the cam lobes contact. Overhead valve engines use rocker arms, which are actuated by a pushrod and pivot on a shaft or individual ball studs in order to actuate the valves.

• Valves

Most modern engines use poppet valves type, although sleeve valves, slide valves and rotary valves have also been used at times. Poppet valves are typically opened by the camshaft lobe or rocker arm, and closed by a coiled spring called a valve spring.

Valve float occurs when the valve spring is unable to control the inertia of the valve train at high engine speeds (RPM)

Parts / 3d model :-

CAM (CASE 1: - 3.5mm Cam lift)

CAM (CASE 2: - 6mm Cam lift)

PUSH ROD :-

ROCKER ARM :-

VALVE :-

VALVE MOUNT :-

Assembly :-

(CASE 1: - 3.5mm Cam lift)

(CASE 2: - 6mm Cam lift)

Explanation :-

• Software used solidworks-2016
• To draw the 3D part, we start from the selecting the part design providing the proper dimension and using proper drawing tools to create the 3d model of the parts for the Valve train assembly
• Now we have the dimensions or the details provided in the video using the same we can obtain the different 3d parts like Cam, pushrod, rocker arm, Valve, etc.
• Using the command Extrude boss base to convert the 2D drawing to 3D & also sometimes we need to use the Revolve boss base for the pushrod & Valve.
• The fallowing parts are shown in the above snap used for the Valve train assembly.
• The next step is to assemble the all parts to obtain a motion between them
• Now to start with the assembly drawing, selecting the parts created for the Valve train assembly and to assemble it using the mating/Mate command
• Inserting one by one part to the assembly drawing, assembly is the process where all the desired generated parts, are assembled to obtain the desire model
• Using the co-incident mate command, the whole setup is properly mated to the desired plane and to the desired axis.
• Now as the part of the challenge for the two different conditions, the motion analysis is going to be carried out as for the cam lift of 3.5mm & 6mm the shape of the cam changes for the following values (2 different cam shapes for the following cam lift values is shown above)
• Now the motion study is calculated for the two different cases for the rotar speed of 1500 rpm
• For each motion study following contact force graph is obtained for Cam and Push rod, Pushrod and Rocker Arm, Rocker Arm and Valve.

• Case 1 :- using the formula for the cam lift we can find the centre distance (L) by considering the values from the video & the cam profile is generated and is then assemble to obtain the motion analysis

The assembly and cam design is shown below

• Case 2 :- using the formula for the cam lift we can find the centre distance (L) by considering the values from the video, here the cam lift given is 6mm so the cam profile generated is slightly different and bigger than the case 1. and then it is assemble to obtain the motion analysis

The assembly and cam profile is shown below

Result & Conclusion :-

• Thus we have studied the MBD Simulation on a IC Engine Valve Train.
• Also modelled all the necessary parts like Cam,Pushrod,Rockerarm & valve and assembled them in solidworks
• Ran the motion analysis study for the two diffrent conditions given in the challange
• Obtained the plots for the contact forces for the Cam and Push Rod,Pushrod and Rocker Arm & Rocker Arm and Valve

• The drive link for the parts and assembly is given below:-

https://drive.google.com/drive/folders/1jaEDkefhvWso-_LzRtAP8perKyRiFUtu?usp=sharing

• The link for the Video on the motion of the valve train assembly is given below:-

Motion Analysis Video :-

FOR CASE 1 :- https://youtu.be/jNF9pBtOb9s

FOR CASE 2 :- https://youtu.be/pdwycqKgLYs

Note :- To view the smooth motion of the Valve train assembly run the video for 0.25x playback speed

• The graphs/plots obtained are shown below :-

Graphs / Plots :-

FOR CASE 1 :-

Combined view of the graphs obtained for the following cases in solidworks

Graph on Valve lift for (CASE 1: - 3.5mm Cam lift)

Contact force between Cam & Pushrod for (CASE 1: - 3.5mm Cam lift)

Contact force between Pushrod & Rocker arm for (CASE 1: - 3.5mm Cam lift)

Contact force between Rocker arm & Valve for (CASE 1: - 3.5mm Cam lift)

Contact force between Rocker arm & Valve for (CASE 1: - 3.5mm Cam lift) (X-direction)

FOR CASE 2 :-

Combined view of the graphs obtained for the following cases in solidworks

Graph on Valve lift for (CASE 2: - 6mm Cam lift)

Contact force between Cam & Pushrod for (CASE 2: - 6mm Cam lift)

Contact force between Pushrod & Rocker arm for (CASE 2: - 6mm Cam lift)

Contact force between Rocker arm & Valve for (CASE 2: - 6mm Cam lift)

Contact force between Rocker arm & Valve for (CASE 2: - 6mm Cam lift) (X-direction)

Conclusion :-

• It is seen that the contact forces increases with the increase in the cam lift

• There is a smooth curve of graph obtained for the valve lift ,showing a periodic cycle

• The contact forces betn the rocker arm and valve differs in the magnitude and in the x direction

• For the plot on x-direction it is seen that the values are changing from the positive to the negative due to the friction as contact force is a frictional value

• For the plot on magnitude, the values plotted are positive as magnitude is always a positive value