Light piston modification

Automobile engine piston is one of the main parts of the engine, it is with piston rings, piston pins and other parts of the piston group, composed and cylinder head combustion chamber and subjected to gas forces the piston pin and connecting rod through the power to pass crankshaft to complete the work process of the internal combustion engine. Because the piston is in poor working environment a high-speed, high pressure and temperature, but also take into account the smooth operation and durability of the engine, thus requiring the piston must also have sufficient strength and stiffness, good thermal conductivity, high heat resistance, low coefficient of expansion (change in size and shape to be small), the relative density (light weight), wear resistance and corrosion resistance, also at low cost. Because the requirements are many and high, some conflicting requirements, it is difficult to find an able to fully meet the requirements of the piston material. Modern engine piston aluminum alloy commonly used as an aluminum alloy material has low density, thermal conductivity, good advantages, but there are expansion coefficient is relatively large, relatively poor high-temperature strength drawbacks only through rational design in order to meet the requirements. Therefore, the quality of the merits of a car engine, not only depends on the materials used, but also depends on the design of rationality.

Pistons are generally cylindrical shape, depending on the engine operating conditions and requirements, the piston itself is configured with a wide variety of generally small things the piston head is divided into three parts, the skirt portion and the piston pin. Is the top of the head and the piston ring groove portions. Depends entirely on the piston to the top of the combustion chamber requires, the use of flat-top or near the top of a flat top piston design helps to reduce the contact area with the high temperature gas, so that the stress distribution. Most gasoline engines use flat pistons, some engines (such as direct injection diesel engine and a new cylinder injection gasoline engine) in order to form the mixture needs to improve combustion efficiency, the deflagration reduced to a minimum, have more complex needs of the piston top shape with a certain depth of the pit as a part of the combustion chamber. The grooves of the piston ring groove is called for mounting piston rings. The role of the piston ring seal to prevent leakage and to prevent the oil into the combustion chamber.

The piston skirt is the lower portion of the piston, its role is to keep the reciprocating motion of the piston in the vertical posture, the guide portion of the piston is. Shape of the piston skirt is very particular about, especially as a light passenger car category, the designer from the structure and performance of the engine starting, often on the piston skirt brains to try to keep the structure stable and compact engine running.

The piston pin bearing portion is connected by a piston pin and the piston rod, the piston skirt portion located above. Special high-speed engine piston pin seat that is not necessarily the piston pin seat hole on the same centerline plane may shift a little bit to one side, namely when making contact with the cylinder wall side of the piston stroke power shift, so when the piston to change the direction of the dead point of the piston hitting the cylinder wall will be the degree of reduction, thereby reducing the engine noise.