【文章內(nèi)容簡介】 wearresistant..Request:1) To have enough rigidity and strength, and the reliable dint。2) Transmit heat well, bear the high pressure, bear the heat and bear to wear away。3) the quantity is small, the weight is light, descend the inertial dint of back and forth as possibleThe aluminum metal alloy material satisfies the top requests basically, therefore, the piston generally adopts the high strength aluminum metal alloy, but some low speed diesel engines adopt high class iron casting or heatproof steelstructure: The piston can be divided into three parts, piston coping, the piston head and piston skirt departments.1. The piston copingThe piston coping bears the air pressure, it is a part of the burnable room .Its shape, position, size are relevant to the concrete from of the burnable room. They are made to satisfy the bustible hybrid spirit formation and burnable requests. Its coping shape can be divided into four major types, a flat coping piston, a convex coping piston, a concave coping piston and model piston.A convex coping piston is usually used on the two blunt distance . engines, It is good to improve the process exchanging the gas .Modern four blunt the distance gasoline machine also adopts the convex coping piston in order to strengthen the effect of pushing the gas or extend the ratio of pressing .Convex of a piston coping presents a form of ball, its coping strength is high, having an effect of leading, being advantageous to improve the process of exchanging the gas, two route of travel gasoline machines often adopt the convex coping piston　　A piston coping presents the hollow form, the shape and positions of the cave pit must be advantageous to the bustion of the bustible and hybrid gas, having a pair of eddies concave pit ball, concave pit, U concave pit, and so on.2. Piston headThe piston refers to the first piston wreath to the part above the piston has several wreath slots, which are used to install the piston wreath and have an effect of sealing pletely. It is also called the leak proof department .The diesel engine’s press ratio is high, and generally have four wreath slots, The three upper wreaths are used to install, the lower part installs the oil wreath. The gasoline machine has three wreath slots generally, which are two jet of gas wreath slots and an oil wreath slots. At the bottom of oil wreath slot many paths toward eyelet are drilled to make the quilt oil wreath flow from the air cylinder wall to the oil bottom hull through these eyelets. The working condition of the wreath slot is the worst and should leave the coping generally a little farther.Above the gas wreath, a narrow insulating slot is usually set to cut off the heat flow which is spread from the piston coping to the first gas wreath and make parts of calories from a piston wreath spread, thus easing the hot burden of the first gas wreath. On some engines small wreathe slots are often made between the coping head and the first gas wreathe, sometimes till a few more wreath. This kind of small wreath can adsorb the lubricant because it accumulates the carbon. It can keep piston and the air cylinder walls from biting to match when it work in the condition of losing oil, so it is called accumulating the carbon slot.The calories that the piston coping absorbs also mainly passes the air cylinder wall through the piston wreath to leak proof department, again spread by the cool a word, the function of the piston head is in addition to install the piston wreath, still seal pletely function and transmit heat function, sealing pletely the air cylinder together with the piston wreath, keeping bustible admixture spirit from leak crankcase, at the same time pass the(7080)%calories to the air cylinder wall through the piston wreath.3. Piston skirt departmentThe piston skirt department refers to the parts from the bottom of the oil wreathe slot. It includes the pin which is used to pack the piston. The piston skirt department exercises to rise to lead to the function to the piston in the back and forth in the air cylinder, and bear the side pressure. The length of the skirt department is decided by the size and the piston diameter of the side pressure. The socalled side pressure mean in the pression route of travel and make route of travel of efficacy .The level ponent of the gas pressure which take effect on the piston coping presses the piston to the air cylinder wall. Compress the route of travel and make the side pressure direction of the efficacy route of travel air exactly the opposite, because of the bustion pressure consumedly high in press the pressure, so, make the side in the route of travel of efficacy pressure also consumedly high in press the side in the route of travel on the sides that bear the side pressure of the piston skirt department be called to push the dint to face, they be placed in to sell the mutually perpendicular direction of the stalk line with piston up.Drive LinesThe drive line includes all the parts from the and final drive carry the torque from the engine, the other. The engine torque during acceleration and the torque during braking place load