MBD Simulation on a Piston Assembly
Piston motion analysis is study of the reciprocating motion of the piston in the cyclinder and the motion of the assembly attached i.e. connecting rod, end cap, crank shaft & gudgeon pin.First of all for the assembly of connecting rod, crank shaft, end cap, gudgeon pin and piston itself we will prepare the geometric model of all the necessary components. The parts required for the assembly is as follows.
Piston: A piston is a component of reciprocating engines, reciprocating pumps, gas compressors and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a piston rod and/or connecting rod.
Gudgeon Pin (Wrist pin): In internal combustion engines, the gudgeon pin connects the piston to the connecting rod and provides a bearing for the connecting rod to pivot upon as the piston moves. In very early engine designs the gudgeon pin is located in a sliding crosshead that connects to the piston via a rod. A gudgeon is a pivot or journal.
Connecting rod: A connecting rod is a rigid member which connects a piston to a crank or crankshaft in a reciprocating engine. Together with the crank. it forms a simple mechanism that converts reciprocating motion into rotating motion.
End cap: End cap is connected to the end of the connecting rod. which is assembled crank.
Crank: Is a mechanical part able to convert the reciprocating motion from the piston into rotational motion.
Final assembly: The piston, connecting rod, wrist pin, end cap and the crank are assembled as shown below using assembly mate option. First the crank is made coincident with the assembly planes so that it can rotate about its axis and then connecting rod and end cap assembly is made coincident with the crank axis. Then wrist pin is made coincident with the piston and with its front plane and it is then assembled to the connecting rod. This will result in the required assembly for the motion analysis.