Abstract: Provided is a valve seat insert made of an iron-base sintered alloy, in which a base matrix part that includes a base matrix phase and hard particles, has a base matrix part composition containing, in % by mass, 0.5%-2.0% of carbon and 10%-70% in total of one kind or two or more kinds selected from nickel, cobalt, chromium, molybdenum, vanadium, tungsten, manganese, silicon and sulfur, with the balance being iron and unavoidable impurities, and Co-base hard particles having a composition containing, 1.0% or less of C, 25%-50% of Mo, 5%-15% of Cr, Si as an impurity in a content adjusted to be 0.3% or less, with the balance being Co, and having a Vickers hardness of 500 to 1,500 HV, are dispersed as hard particles in the base matrix phase in an amount of 10%-60% by mass with respect to the total amount of the valve seat insert.

Abstract: Provided is a valve seat insert made of an iron-base sintered alloy, in which a base matrix part that includes a base matrix phase and hard particles, has a base matrix part composition containing, in % by mass, 0.5%-2.0% of carbon and 10%-70% in total of one kind or two or more kinds selected from nickel, cobalt, chromium, molybdenum, vanadium, tungsten, manganese, silicon and sulfur, with the balance being iron and unavoidable impurities, and Co-base hard particles having a composition containing, 1.0% or less of C, 25%-50% of Mo, 5%-15% of Cr, Si as an impurity in a content adjusted to be 0.3% or less, with the balance being Co, and having a Vickers hardness of 500 to 1,500 HV, are dispersed as hard particles in the base matrix phase in an amount of 10%-60% by mass with respect to the total amount of the valve seat insert.

Abstract: There are disclosed a laser clad valve seat raw-material powder superior in productivity, cladding property, wear resistance and finishing property, and a laser clad valve seat using the same superior in wear resistance. The row-material powder comprises a powder mixture comprising: 80 to 99% by weight of a Cu-based alloy powder comprising 0.5 to 5% by weight of B, 0 to 20% by weight of Ni, 0 to 10% by weight of Fe plus Co, 0 to 5% by weight of Si, 0 to 3% by weight of Al, and the balance Cu and unavoidable impurities; and 1-20% by weight of an Fe or Co based alloy powder having a Vickers hardness of 500 HV or higher and an average particle diameter of 50 to 200 ?m of and comprising 5 to 40% by weight of Mo, 0 to 25% by weight of Cr, 0 to 5% by weight of Si, and the balance Fe or Co and unavoidable impurities.

Abstract: There are disclosed a laser clad valve seat raw-material powder superior in productivity, cladding property, wear resistance and finishing property, and a laser clad valve seat using the same superior in wear resistance. The row-material powder comprises a powder mixture comprising: 80 to 99% by weight of a Cu-based alloy powder comprising 0.5 to 5% by weight of B, 0 to 20% by weight of Ni, 0 to 10% by weight of Fe plus Co, 0 to 5% by weight of Si, 0 to 3% by weight of Al, and the balance Cu and unavoidable impurities; and 1-20% by weight of an Fe or Co based alloy powder having a Vickers hardness of 500HV or higher and an average particle diameter of 50 to 200 ?m of and comprising 5 to 40% by weight of Mo, 0 to 25% by weight of Cr, 0 to 5% by weight of Si, and the balance Fe or Co and unavoidable impurities.

Abstract: An iron-based sintered alloy material for a valve seat having improved wear resistance and reduced opposite aggressibility to a mating valve. The iron-based sintered alloy material contains 10% to 20% by area of first hard particles and 15% to 35% by area of second hard particles dispersed in a base matrix phase, the first and the second hard particles accounting for 25% to 55% by area in total. The first hard particles are composed of a cobalt-based intermetallic compound and have a size of 10 to 150 ?m and a hardness of at least 500HV0.1 and less than 800HV0.1. The second hard particles are composed of a cobalt-based intermetallic compound and have a size of 10 to 150 ?m and a hardness of at least 800HV0.1 and less than 1100HV0.1. Solid lubricant particles may also be dispersed in the base matrix phase.

Abstract: An iron-based sintered alloy material for a valve seat having improved wear resistance and reduced opposite aggressibility to a mating valve. The iron-based sintered alloy material contains 10% to 20% by area of first hard particles and 15% to 35% by area of second hard particles dispersed in a base matrix phase, the first and the second hard particles accounting for 25% to 55% by area in total. The first hard particles are composed of a cobalt-based intermetallic compound and have a size of 10 to 150 ?m and a hardness of at least 500HV0.1 and less than 800HV0.1. The second hard particles are composed of a cobalt-based intermetallic compound and have a size of 10 to 150 ?m and a hardness of at least 800HV0.1 and less than 1100HV0.1. Solid lubricant particles may also be dispersed in the base matrix phase.

Abstract: A tensioner for an endless transmitting member is provided to reliably prevent the loosening of an endless chain, while preventing the occurrence of an incorrect meshing of the endless chain with sprockets. A plunger holder is biased in an advancing direction by the action of a first spring supported in a housing, and a plunger, carried in the plunger holder, is biased in an advancing direction by the action of a second spring having a spring constant larger than that of the first spring. Only the movement of the plunger holder in the advancing direction is permitted by a ratchet mechanism mounted between the plunger holder and the housing. During operation of the engine, the advancing movement of the plunger holder is inhibited by the hydraulic pressure transmitted to a hydraulic pressure chamber, and the plunger is advanced and retracted in accordance with a variation in tension of the endless chain.

Abstract: An engine has two balancer shafts supported on two bearing bushings which are made of the same material and mounted to a balancer holder. Lubricating oil passages for supplying oil to the bearing bushings are defined offset upwards from the centers O of the bearing bushings and by a distance .delta.. Each of the bearing bushings has two oil bores having a center angle .theta. other than 180.degree.. The two oil bores in the bearing bushing of one balancer shaft communicate with the lubricating oil passage, and one of the oil bores in the bearing bushing of another balancer shaft communicates with the lubricating oil passage, while the other oil bore of that another balancer shaft is closed to keep out of the lubricating oil passage. Thus, downstream ends of the lubricating oil passages for supplying the oil to the bearing bushings of the plurality of rotary shafts can be closed without use of a special closing member such as a blind plug.

Abstract: An engine having a lower block made of an aluminum-based material and having a bearing cap mounted therein in a cast-in manner abutting against front and rear sidewalls of a cylinder block of the engine and coupled to the cylinder block by a bolt, and a pump body is coupled to a lower surface of the lower block by bolts. The pump body also serves as a balancer shaft supporting member, and a journal portion of a balancer shaft is supported on the balancer shaft supporting member. Thus, the rigidity of supporting of the balancer shaft on the balancer shaft supporting member can be enhanced without an increase in size of the balancer shaft supporting member of the engine.

Abstract: A valve operating device for use in an internal combustion engine for varying operating characteristics of a pair of engine valves (20) in multi-stages depending upon operating conditions of the engine. A cam shaft (31) is provided with a high-speed cam (32), a pair of medium-speed cams disposed on opposite sides of the high-speed cam (32), and a pair of low-speed cams (34) disposed between the medium-speed cams (33) and the high-speed cam (32). A rocker shaft (35) is provided with a first free rocker arm (36) in sliding contact with the high-speed cam (32), a pair of driving rocker arms (37) operatively connected to the pair of engine valves (20), respectively, and in sliding contact with the low-speed cams (34), and a pair of second free rocker arms (38) disposed with the driving rocker arms (37) interposed between the second free rocker arms (38) and the first free rocker arm (36) to be in sliding contact with the medium-speed cams (33).