Abstract: An auxiliary device for installing piston rings is described, which includes a mounting base, a transmission device, a connecting rod and a bracing structure. The mounting base includes a platform, an opening hole and an accommodating space. The transmission device is disposed in the accommodating space and includes a guide screw rod, a sliding base and a motor. The sliding base is slidably screwed on the guide screw rod. The motor can drive the guide screw rod to move the sliding base. The connecting rod is disposed on the sliding base. An external diameter of the piston ring while being put around the connecting rod is greater than an inner diameter of the opening hole. The bracing structure is disposed on the connecting rod. An external diameter of the bracing structure is getting greater from one end connected to the connecting rod. The bracing structure can accommodate the piston.

Abstract: A structure of a piston ring to be installed in an engine includes a matrix. A laminated intermediate layer is formed on a surface of the matrix from hard chromium (Cr), chromium nitride (CrN) and titanium carbide (TiC) in order, and a diamond-like carbon film (DLC) is coated on an outer periphery of the intermediate layer. Thus, the piston ring is wrapped by a skin with a progressive structure having a gradient distribution of hardness. The structure formed from the diamond-like carbon film provides a low wear rate and a low friction coefficient, while applying a high bonding force to the matrix and making the piston ring have an improved normal service life that meets the related environmental regulations.

Abstract: Provided is an oil-control ring mounted around a ring-groove of a piston of a gasoline engine. The oil-control ring comprises an upper first thin ring having a gap, an upper second thin ring having a gap, a lower first thin ring having a gap, a lower second thin ring having a gap, and an intermediate main ring, wherein the gap of the upper first thin ring is not aligned with the gap of the upper second thin ring and the gap of the lower first thin ring is not aligned with the gap of the lower second thin ring. A plurality of embodiments of the main ring are made possible.