| 摘要 |
PURPOSE:To improve the durability of an oil ring and a coil expander by forming the nitrided external face of the coil expander combined with the oil ring fixed onto a piston of an internal combustion engine. CONSTITUTION:An oil ring 1 is stuck into the circumference of a piston giving no illustration of it. A coil expander 2 circular, rectangular or trapezoidal in section is situated in the bottom of the ring so that the ring 1 can make constant contact with a cylinder liner giving no illustration of it. The internal circumference 12 of the ring and the external circumference 21 of the expander meet in contact with the ring 1 and the expander 2. A nitride 22 is formed over both the internal and external circumferences 12, 21 to improve the stiffness at the contact area. |
