One. Enter air travel
Right now, the piston is driven by crankshaft be down shift of top dead centre by top dead centre, in the meantime, inlet valve open, exhaust valve is shut. When the piston is down dead centre to move by top dead centre, the cubage of piston upper part increases, the aeriform pressure inside air cylinder drops, form certain vacuum to spend. As a result of inlet valve open, air cylinder and air inlet duct are interlinked, mixture gas by inspiratory air cylinder. When the piston shift arrives when next dead centre, was full of inside air cylinder fresh mixture gas and loop of a job not the waste gas of eduction.
2. Reduce the travel
The piston moves by next dead centre top dead centre, shut into exhaust valve. Crankshaft is driven below the action of the force such as flywheel rotate, drive a piston to move up through connecting rod, cubage of the gas inside air cylinder is reduced gradually, gas is compressed, the mixture air pressure inside air cylinder and temperature as elevatory.
3. Combustion expands the journey
Right now, shut at the same time into exhaust valve, sparkplug ignition, mixture gas is acuteness burn, the temperature inside air cylinder, pressure rises quickly, gas of high temperature, high pressure drives a piston to be down shift, drive crankshaft to rotate through connecting rod. In 4 journeys that work in engine, only this just achieves mechanical energy of heat energy translate into in the journey, so, this journey is called again do work the journey.
4. Exhaust journey
Right now, exhaust valve is opened, the piston moves from next dead centre top dead centre, waste gas as the piston go up, by eduction air cylinder. Because exhaust system has resistance, and firebox also has certain volume, be in exhaust cease ground so, discharge waste gas impossibly clean, the waste gas that this part stays calls residual gas. Residual gas is affected not only aerate, also have undesirable effect to burning.
When exhaust journey ends, the piston returned top dead centre again. Also finished loop of a job. Subsequently, crankshaft relies on the inertial action with rotational flywheel to still continue to rotate, begin next circulation. Such go round and round, engine runs ceaselessly rise.