Abstract: A cylinder liner for insert casting used in a cylinder block is provided. The cylinder liner includes an outer circumferential surface having a plurality of projections. Each projection has a constricted shape. A film of a metal material is formed on the outer circumferential surface and the surfaces of the projections. As a result, the cylinder liner ensures sufficient bond strength with the casting material of a cylinder block, and sufficient thermal conductivity with the cylinder block.

Abstract: A cylinder liner for insert casting used in a cylinder block is provided. The cylinder liner includes an outer circumferential surface having a plurality of projections. Each projection has a constricted shape. A film of a metal material is formed on the outer circumferential surface and the surfaces of the projections. As a result, the cylinder liner ensures sufficient bond strength with the casting material of a cylinder block, and sufficient thermal conductivity with the cylinder block.

Abstract: A combined oil ring comprises an oil ring and a coil expander. A curved bar passes through paired end portions of the coil expander. An antirotation member comprises a portion to be inserted into a hole and a portion to be held. Two mutually parallel surfaces of the portion to be held are held between paired end surfaces of the coil expander while the portion to be inserted into a hole is inserted into an antirotation member securing hole formed at the bottom surface of an oil ring groove of a piston. The curved bar passes through a curved bar insertion hole formed in the portion of the antirotation member to be held.

Abstract: Using an arc ion plating apparatus, a metal not capable of forming a carbide or nitride, such as cobalt, nickel or molybdenum is set as a first target, a metal capable of forming a carbide or nitride, such as silicon, titanium, vanadium, chromium, iron, zirconium, niobium or tungsten is set as a second target and nitrogen, acetylene or methane is fed as a process gas to form a film on a piston ring body which is an article to be coated, thereby providing a piston ring comprising a hard film formed on at least its sliding outer face of the piston ring body, said hard film comprising a mixed structure formed of the metal not capable of forming a carbide or nitride and a carbide or nitride of the metal capable of forming a carbide or nitride. In this piston ring, the hard film has so good adhesion to the body material or film toughness that no cracking or film separation tend to occur even when the film is formed in a large thickness.

Abstract: A piston ring is made of a titanium alloy, at least an outer peripheral surface and upper and lower surfaces thereof are formed with a nitrogen diffused layer, and at least an outer peripheral sliding surface thereof is coated with a hard film by physical vapor deposition on the nitrogen diffused layer.

Abstract: A piston ring comprises a martensitic stainless steel ring having a nitrided layer formed in the surface portion thereof, and a titanium nitride film coated on the outer sliding surface of the ring by an ion-plating process. According to a first embodiment of the present invention, the titanium nitride film has a nitrogen concentration which is gradually increased toward the top surface thereof to gradually lower a toughness of the film toward the top surface and to make a surface portion of the film more brittle than the other portion of the film. On the other hand, according to a second embodiment of the present invention, the titanium nitride film has a nitrogen concentration which is gradually decreased toward the top surface and to make a surface hardness of the film HV 1800 or less.