Abstract: The present invention relates to a piston ring (10), particularly a compression ring, for an internal combustion engine, comprising a ring-shaped body (11) having a ring joint (13) formed by butt ends (14a, 14b), the ring-shaped body (11) further having a ring contact face (12) along its perimeter, for contacting a cylinder wall in operation. According to the invention, the ring contact face (12) has a barrel-shaped profile, the barrel-shaped profile having in any of its cross-sections an area of maximum curvature, whose radius of curvature increases in the direction of the butt ends (14a, 14b).

Abstract: An oil-control ring for an internal combustion engine, to be mounted between the sidewalls of a respective groove of a piston has two ring segments and an annular expander disposed between the two ring segments and presenting a support body defining a seating plane for each ring segment. The ring has at least one expander portion axially projecting from the support body of the expander, beyond at least one of the seating planes of a ring segment, and at least one superficial irregularity provided in at least one of the ring segments and which is dimensioned to be contained in the thickness of the respective ring segment and to interfere with at least one expander portion, in order to rotatively lock the ring segment in relation to the expander.

Abstract: The invention relates to a piston ring for internal combustion engines, the piston ring comprises a steel or cast iron base material with a coating of chromium nitride deposited by a physical vapor deposition process on a sliding surface of the piston ring, wherein the coating is composed of a columnar crystal structure of CrN with the following features: (a) an oxygen content in solid solution of 0.5 to 2.5 wt %; (b) a content of uniformly dispersed micro-pores of less than 10% in volume of the coating; and (c) an X-ray diffraction intensity ratio of (111) planes to (200) planes parallel to the surface in the range of 0.80 to 1.20.

Abstract: The present invention relates to a piston ring for an internal combustion engine, the piston ring comprises a sulphide rich compound layer forming a surface layer, said sulphide rich compound layer comprising an iron nitride matrix with iron sulphide (FeS) inclusions embedded in said matrix, said sulphide rich compound layer having a sulphur content of 1 to 4 wt % S and a nitrogen content of 10 to 20 wt % N.

Abstract: The present invention provides a piston for an internal combustion engine. The design of the piston is such that the contact between the piston ring and the groove, during operation and especially in the moments of higher pressure on the ring, is as distributed as possible, in order to minimize the wear rate of the lateral walls of the groove.

Abstract: A bimetallic strip for a sliding bearing having a sliding strip of an aluminum alloy which is adhered to a steel supporting strip and method of manufacture. The composition of the sliding strip is from 3 to 30% of tin; from 1 to 6% of silicon and the remainder being of aluminum and impurities, and the sliding strip has at least 95% of the silicon hard particles smaller than 3.5 microns and an aluminum grain average size of about 6 microns. The sliding strip is produced by roll casting the alloy and attaching the sliding strip to the steel supporting strip to form the bimetallic strip which is heat treated between 200° and 380° C. to obtain a metallurgical bonding between the strips; subjecting the bimetallic strip to a solubilizing process of the intermetallic compounds of the aluminum alloy by heating at 380-500° C., followed by cooling; and subjecting the bimetallic strip to a precipitation treatment at a temperature from 150° to 250° C.

Abstract: A piston which has a diameter of about 70 to about 100 mm and which is preferably produced with a resistant, malleable alloy having low density (lower than about 3 g/cm.sup.3) and mechanical properties at high temperatures such that a yield stress greater than about 120 Mpa at temperatures of the order of 300.degree. C. to 350.degree. C. is obtained. In the preferred embodiment, the piston is a single piece piston, comprising a head portion of diameter D ranging from about 70 to about 100 mm and a skirt portion downwardly projected from the head portion and inside which is provided a pair of wrist pin bosses, each having a hole with a diameter d and axial extension L for bearing the articulating wrist pin of the piston.

Abstract: Wrist pin for a two-piece piston, having a cylindrical external surface (41) and an internal surface with an internal diameter, throughout the length of the pin (40). The end portions of the pin have a reduced internal wall thickness between the outer half of the supporting face of the bosses (50), where there exclusively occur bending moment and shearing force applied by the inertia of the skirt (20) and of the moving assembly (100). The reduction in the internal wall thickness is obtained by the increase in the internal diameter of the pin (40) at the end portions, through two different end revolution surfaces (43, 44) each having respective a generatrix which is at least substantially straight.

Abstract: A two-piece, or articulated, piston head for internal combustion engines having top and pin boss portions in which the underside of the top portion is provided with a groove whose inner wall is eccentric in relation to the longitudinal axis; of the top and the upper side of the top portion is provided with a combustion bowl eccentric in relation to the top portion longitudinal axis and concentric with the inner wall of the groove on the underside of the top portion.

Abstract: Piston with a reinforcing insert, presenting a top face (11) with a recessed combustion chamber (12) provided with a lateral peripheral wall, defined by the annular insert (20), which presents an internal end face (24) with a radial extension (d.sub.1) that is substantially smaller than the radial extension (d.sub.2) of the opposite external end face (22) of the annular insert (20). The radial thickness of the insert (20) varies along the profile of its external peripheral face (23), in order to maintain a value necessary to meet the requirements of structural reinforcement of the piston (10), at the region where the insert (20) is applied.

Abstract: A cooled piston head and method of manufacture, the piston head having a closed cooling chamber. In one embodiment, the piston head is formed of a top member, an intermediate member and a pin boss member joined to each other preferably by welding; the top and intermediate members are provided with circumferential grooves which defines the closed cooling chamber. In an alternate embodiment, the head is formed of a top member and a pin boss member joined together preferably by welding; the closed cooling chamber is defined by circumferential grooves provided on both members.

Abstract: A method to manufacture an articulated piston head wherein the two portions composing the head, i.e. the top portion and the pin boss portion, are formed separately from blanks of forged or cast chromium-molybdenum steel or a low alloy steel, subjected to preliminary machining operations, joined together by friction welding and then machined to final dimensions.

Abstract: A method for the manufacture of a cooled piston head in which the upper and lower portions of the piston head are made separately a metal plate is placed on the lower side of the upper portion; then the upper portion incorporating the metal plate is joined to the lower portion by friction welding. The metal plate is provided with a central hole for the passage of cooling oil onto the undercrown, and means of communication with a closed cooling chamber defined by a circumferential groove on the head upper portion and the peripheral outer surface of the metal plate.

Abstract: A cooled piston head and method of manufacture, the piston head having a closed cooling chamber. In one embodiment, the piston head is formed of a top member, an intermediate member and a pin boss member joined to each other preferably by welding; the top and intermediate members are provided with circumferential grooves which defines the closed cooling chamber. In an alternate embodiment, the head is formed of a top member and a pin boss member joined together preferably by welding; the closed cooling chamber is defined by circumferential grooves provided on both members.

Abstract: A sliding bearing (10) having an inner surface (13a) provided with at least one circumferential recess (15, 16) extending over a portion of the axial dimensions of the inner surface (13).The recess (15, 16) is located over one portion of the inner surface (13a) which is subjected to a peak oil film pressure (POFP) higher than a minimum value previously calculated for, and/or located up to 45 degrees upstream considering the rotation direction of the shaft, in one region of the inner surface (13a) where the minimum oil film thickness (MOFT) is less than a value previously calculated. Each circumferential recess (15, 16) is defined by a maximum radial depth E, a circumferential range given by the angle .alpha., which vary according to construction and operational features of the bearing (10), in order to cause the values of pressure and/or oil film thickness to meet values previously calculated for the bearing (10).

Abstract: A two-piece, or articulated, piston head for internal combustion engines and the method for obtaining same. The top and pin boss portions composing the head are obtained separately from blanks; the underside of the top portion is provided with a groove whose inner wall is eccentric in relation to the top longitudinal axis; the two portions are joined together by welding; the upper side of the top portion is provided with a combustion bowl eccentric in relation to the top portion longitudinal axis and concentric with the inner wall of the groove on the underside of the top portion.

Abstract: A method for the manufacture of a cooled piston head in which the upper and lower portions of the piston head are made separately; a metal plate is placed on the lower side of the upper portion; the upper portion incorporating the metal plate is joined to the lower portion by friction welding. The metal plate is provided with a central hole for the passage of cooling oil onto the undercrown, and means of communication with a closed cooling chamber defined by a circumferential groove on the head upper portion and the peripheral outer surface of the metal plate.

Abstract: A method for the manufacture of a piston head having a cooling chamber is disclosed. The two portions composing the piston head are made separately; the underside of the upper portion is provided with a circumferential peripheral groove; notches are provided on both sides of the open end of the circumferential peripheral groove; a circumferential annular plate is placed on the notches thereby closing the circumferential peripheral groove; the two portions making up the head are joined to each other by welding and cause the inner edge of the annular plate to be retained in the piston head and become an integral part thereof.

Abstract: A bearing halfshell for internal combustion engine connecting rods with its inner surface having a substantially constant radius of curvature from a central plane of symmetry to two portions of the inner surface located one on each side of the central plane of symmetry and on a corresponding radial plane. The radial plane forms an acute angle .alpha. with a bearing parting plane, the remaining end portions of the inner surface from the radial plane to the end of the bearing being defined by surfaces with extra relief so that the bearing thickness gradually decreases away from the central plane of symmetry in an accentuated manner as compared to the constant radius of curvature of the inner surface. Thereby, two chambers are formed in the end portions, with an eccentricity .epsilon., of the inner surface ensuring a stable film of oil between the bearing halfshell and a corresponding shaft, and reducing the operating temperature of the bearing halfshell.

Abstract: A method of making a plain bearing sliding layer for use in internal combustion engines, comprising the immersion of a metal substrate in a chemical solution containing copper, tin and lead salts to which is added one of the compounds represented by the following three exemplary structures: ##STR1## where X is one of the chemical elements selected from sulphur and nitrogen, --C represents one carbon atom, and radicals R.sub.1 and R.sub.2 represent the allowed variations, from a single hydrogen atom up to the typical structures of inorganic compounds or aliphatic, aromatic or cyclic chain organic radicals. The chemical solution is subjected to an electric current with a density and potential controlled as a function of time, thereby effecting the selective electrodeposition of the solution elements on the substrate so as to form successive and alternate layers of softer material and harder material.