Causes the piston to burn the roof the reason to have the following several points:
1 piston top coke serious. Carbon piston top of the piston top local overheating and high temperature, when the local high temperature than the melting point, will melt to form melting hole of piston top.
2 piston ring cemented or broken. The piston ring glued or fracture will lead to piston ring and cylinder wall can be tightly attached on the top of piston heat can not pass, but also guide the high temperature gas channeling, the piston and piston ring groove position because of overheating and ablation.
3 fuel supply uneven. The cylinders of diesel engine oil and oil time if not uniform, will make part of the cylinder combustion process of coke formation or serious deterioration, after burning, diesel combustion heat can not be used to do work, and make the piston in the cylinder part of the top temperature is too high, leading to thermal fatigue and burning.
4 bad fuel injector. When the fuel injection nozzle drops, the two injection and the atomization are bad, the local temperature is too high, the thermal stress is increased, and the thermal stress of the piston is increased.
5 engine knock. Engine, piston top bear periodic mechanical shock burning explosive force, the instantaneous impact is up to 7MPa, directly on the top of the piston impact force of up to 100kN above. If the engine is knocking, the impact force will increase exponentially. Thermal fatigue and mechanical fatigue are produced under the action of thermal stress and periodic burning of the piston. Cause engine knock is mainly supply time or premature ignition time, the cylinder inner product too much Coke and compression ratio is too high, the top of the piston form caused by early burning, blazing hot gasoline octane number too low.
6 oil cooling nozzle clogging. Some high power engine body is provided with an engine oil cooling nozzle, which is injected through the inner cavity of the piston to help the cooling and heat radiation. If the oil cooling nozzle clogging, the piston will heat up, but also easy to cause the piston to burn the roof.
7 engine for a long time overload, or poor heat engine. Piston has long been highly thermal stress and mechanical stress, easy to fatigue ablation.
8 piston quality is not qualified. If the piston casting pores, porosity, cracks, slag and other defects, then under the high temperature, the porosity, and micro cracks will become the source of fatigue and cause fatigue damage; piston slag in first melt, causing the piston burning.
9 often fierce boom throttle, engine speed and high load operation, the temperature is too high.
For these reasons the piston top burning analysis can know that the key to prevent the piston top burn is to strengthen the maintenance of the engine, the engine is always kept in good technical condition, to avoid overheating, coke, deflagration to detonation phenomenon of the engine; the correct use, to avoid engine overload.