The skirt of the
New Car piston refers to the part from the lower end face of the oil ring groove to the lowest end of the piston, which includes the pin seat hole for the piston pin. The skirt of the New Car piston guides the reciprocating motion of the piston in the cylinder and bears the side pressure. The length of the skirt depends on the size of the side pressure and the diameter of the piston.
The so-called side pressure refers to the horizontal component of the gas pressure acting on the top of the piston during the compression stroke and the power stroke, which presses the piston against the cylinder wall. The side pressure direction of the gas in the compression stroke and the power stroke is exactly opposite. Since the combustion pressure is much higher than the compression pressure, the side pressure in the power stroke is also much higher than the side pressure in the compression stroke. The two sides of the
Fuel Car piston skirt that bear the side pressure are called thrust surfaces, which are in a direction perpendicular to the axis of the piston pin.
In order to make the two sides of the skirt bear the gas pressure and maintain a small and safe gap with the cylinder, the piston is required to have a correct cylindrical shape when working. However, due to the uneven thickness of the piston skirt of a Fuel Car, the metal in the piston pin seat hole is thick, which expands greatly due to heat, and the deformation along the piston pin seat axis is greater than in other directions. In addition, the skirt is subjected to the pressure of the gas side, resulting in a greater deformation along the piston pin axis than in the direction perpendicular to the piston pin.
