Abstract: Provided are a valve guide made of an iron-based sintered alloy excellent in wear resistance and thermal conductivity, and a method of producing the same. Specifically, provided are a method of producing a valve guide made of an iron-based sintered alloy, the method including the steps of: molding raw material powder including diffusion-alloyed powder including core iron powder and Cu bonded to the core iron powder through diffusion to obtain a molded body; and sintering the molded body, to thereby produce a valve guide made of an iron-based sintered alloy, and a valve guide produced by the production method.

Abstract: Provided are a valve guide made of an iron-based sintered alloy excellent in wear resistance and thermal conductivity, and a method of producing the same. Specifically, provided are a method of producing a valve guide made of an iron-based sintered alloy, the method including the steps of: molding raw material powder including diffusion-alloyed powder including core iron powder and Cu bonded to the core iron powder through diffusion to obtain a molded body; and sintering the molded body, to thereby produce a valve guide made of an iron-based sintered alloy, and a valve guide produced by the production method.

Abstract: A cooling system for a piston of an internal combustion engine includes a cooling channel (34) designed as an oil passage embedded in the piston and arranged adjacent to a top ring groove, and an oil supply portion (8) that supplies oil to the cooling channel. An amount of oil supplied from the oil supply portion to the cooling channel is made larger when an amount of heat generated in a combustion chamber is large than when the amount of heat generated in the combustion chamber is small.

Abstract: Each of a plurality of cylinder liners has a cooling liquid groove at its outer circumferential surface and has a flat surface over an entire axial length at a part of the outer circumferential surface. The cylinder liners are inserted in bores of a cylinder block with flat surfaces of adjacent liners abutting each other and the grooves at the flat surfaces being coincident with each other.

Abstract: A cylinder liner comprises an outer circumferential surface provided with a plurality of groups of annular grooves, a longitudinal groove communicating the annular grooves with each other and forming an outlet for a cooling liquid in each of the groups of annular grooves, and a longitudinal groove communicating the annular grooves with each other and forming an inlet for the cooling liquid in each of the groups of annular grooves. The outlet communicates in series with the inlet in the adjoining groups of annular grooves. Sectional areas of the annular grooves in the same group of annular grooves are decreased from an upstream side toward a downstream side.

Abstract: A cylinder liner is fitted in a cylinder bore of a cylinder block of a multiple-cylinder engine. The cylinder liner has an outer circumferential surface having a plurality of annular grooves and a plurality of longitudinal grooves connected thereto, in which a cooling liquid is flowed in the grooves. A part in an axial direction of a crankshaft of a bottom of at least one of the annular grooves is coated with a sprayed coating of metal, and a sectional area of the annular groove provided with the sprayed coating varies in a circumferential direction.

Abstract: A cylinder liner having an outer circumferential surface having a plurality of groups of annular grooves, wherein each of the groups of annular grooves has two longitudinal grooves communicating the individual annular grooves with each other, forming an outlet and an inlet for the cooling oil and disposed at locations spaced apart by 180.degree. in a circumferential direction, and the outlet communicates with the inlet in series in the adjoining groups of annular grooves. The outer circumferential surface has further a longitudinal groove connected to the lower end of the longitudinal groove forming the outlet of the lowermost group of annular grooves, a circumferential groove connected to the lower end of the longitudinal groove, and a longitudinal groove having the upper end connected to the circumferential groove and the lower end released, and the lowermost longitudinal groove is disposed at a circumferential position differing from the longitudinal grooves in the groups of annular grooves.