Nippon Piston Ring Co., Ltd.

Honda Motor Co., Ltd.

Nittan Valve Co., Ltd.

Sanyo Special Steel Co., Ltd.

Hiroshi Oshige

Kenichi Sato

Satoshi Ikemi

Seisuke Takaki

Kiyoshi Suwa

Ayato Oikawa

Toshiyuki Sawada

Keisuke Ishii

Teruo Takahashi

Katsuaki Ogawa

Osamu Kawamura

Tomoki Okita

Hiroyuki Hasegawa

Takashi Kawamoto

Kouji Kunitake

Ryouichi Yoshino

Takeshi Haniu

Provided is a valve seat insert for an internal combustion engine, which has both an excellent heat dissipation property and excellent wear resistance. The valve seat insert for an internal combustion engine is used while being press-fitted into an aluminum alloy cylinder head, is made of an iron-based sintered alloy, is formed by integrating two layers of a functional member side layer and a supporting member side layer, and has a plating film on at least an outer peripheral side. The plating film is preferably a copper plating film. The plating film is a plating film having a thickness of 1 to 100 &#x3bc;m and a hardness of 50 to 300 HV, and the hardness of the plating film is adjusted so as to satisfy a range of 1.05 to 4.5 times hardness of the cylinder head in Vickers hardness HV. Pores contained in the valve seat insert are preferably sealed with a curable resin before plating treatment. Consequently, a valve seat insert for an internal combustion engine which does not go through complicated processes, is not accompanied by a significant decrease in wear resistance compared with the prior art, and has an excellent heat dissipation property is provided. If a roughened surface region is further formed at at least one portion on the outer peripheral surface of the valve seat insert in addition to the plating film, a falling out resistance property is improved. The same effect can be obtained even if the valve seat insert is a single layer of only the functional member side layer.

Iron-based sintered alloy valve seat for internal combustion engine

A valve seat insert made of an iron-base sintered alloy is configured to have a structure in which the base matrix phase is a fine carbide precipitation phase in which a fine carbide being 10 &#x3bc;m or less in size is precipitated and which has a hardness of 550 HV or more in Vickers hardness; and in the base matrix phase, hard-particles having a hardness of 650-1200 HV in Vickers hardness are dispersed in an area percentage of 20-40%, a diffusional phase is formed in an area percentage of more than 0% and not more than 5%, and solid-lubricant particles are dispersed in an area percentage of 0-5%. Even if a valve having a high face hardness of 400 HV or more, or 600 HV or more is used, a facing valve seat insert wears only slightly, improving valve train durability.

Valve seat insert excellent in wear resistance made of iron-base sintered alloy for internal combustion engines, and assembly of valve seat insert and valve

A highly wear-resistant valve seat insert for an internal combustion engine, having a material composition in which hard-particles are uniformly and finely dispersed in the matrix phase, and which is excellent in wear-resistance and radial crushing strength, based on a blended fine powder and a matrix forming powder with a particle size approximately equal to that of the hard-particles so as to prevent the hard-particles from aggregating and thus coarsely dispersing as a hard-particle phase.

Highly wear-resistant valve seat for use in internal combustion engine

In an assembly of a hollow poppet valve and a valve seat insert, the hollow poppet valve's head is integrally formed with a stem end, a hollow part is formed from the head to a stem, and coolant is filled into the hollow part along with an inert gas. The valve seat insert is formed of iron base sintered alloy and obtained by integrating two layers of a supporting material side layer and a valve contact face side layer. The hollow poppet valve is formed of a material having thermal conductivity of 5-45 (W/m&#xb7;K) at 20-1000&#xb0; C. The valve seat insert includes the supporting material side layer having thermal conductivity of 23-50 (W/m&#xb7;K) at 20-300&#xb0; C. and a valve contact face side layer having thermal conductivity of 10-22 (W/m&#xb7;K) at 20-300&#xb0; C. This enables a valve temperature decrease throughout an engine's entire RPM range compared with the prior art.

Assembly of internal combustion engine valve and valve seat

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.

Valve seat insert for internal combustion engine having excellent wear resistance

An iron-base sintered alloy material includes a matrix phase, Co base inter-metallic compound particles having hardness of 600 to 1200 HV, carbide-type particles having hardness of 400 to 700 HV, and optionally solid-lubricant particles, the particles being dispersed in the matrix phase. A matrix part including the matrix phase and the two kinds of hard-particles contains 0.3 to 1.5% by mass of C, and 10 to 50% by mass of one or more kinds selected from Si, Mo, Cr, Ni, Co, Mn, S, N, V, Ca, F, Mg, and O, the balance being Fe and unavoidable impurities. By dispersing, in the matrix phase, the Co base inter-metallic compound particles having high hardness, and the carbide-type particles having low hardness and low aggressiveness to mated material and increasing mechanical strength, wear-resistance can be improved with low aggressiveness to mated material and high radial crushing strength (350 MPa or more).

Iron-base sintered alloy material for valve seat insert and method for manufacturing the same

It is an object of the present invention to provide a valve seat product in which the amount of hard particles added to improve the wear resistance of a valve seat of an internal combustion engine is increased, and is excellent in the mechanical strength and machinability. In order to achieve the object, an iron-based sintered alloy material for a valve seat is employed which is made to contain a first hard particle having an average primary particle diameter of 5 to 20 &#x3bc;m and a second hard particle having an average primary particle diameter of 20 to 150 &#x3bc;m in a texture, wherein a particle size distribution curve measured by laser diffraction scattering analysis has N peaks (N is an integer equal to or larger than 2) and when particle diameters corresponding to the peak top positions are denoted as Dto D, a peak top particle diameter difference between neighboring Dand D(|D&#x2212;D|: n is an integer equal to or larger than 2 and equal to or smaller than N) is in the range of 15 to 100 &#x3bc;m in at least one neighboring Dand D; and the total area ratio occupied by both of the first hard particle and the second hard particle constituting the mixed hard particle in the texture of the iron-based sintered alloy is 10 to 60% by area.

Iron-based sintered alloy for valve seat, and valve seat for internal combustion engine

An internal combustion engine includes, in combination, an intake side valve system and an exhaust side valve system. Each of the valve systems comprises a valve seat and a valve member to be assembled with the valve seat, in which the valve seat has a base member including a matrix of iron-base sintered alloy and a dispersed Si&mdash;Cr&mdash;Mo&mdash;Co group intermetallic compound powder, the intermetailic compound powder having a hardness of Hv600 to Hv1000 and an average particle diameter of 20 to 70 &mgr;m, the matrix being contained at 10 to 50 mass % with reference to total mass of the base member, and the valve member has a base member including a matrix of martensitic steel and a nitriding diffusion layer formed to a valve face of the base member, the nitriding diffusion layer having a hardness of more than Hv500 and a thickness of more than 20 &mgr;m.

Valve system for internal combustion engine

A process for manufacturing a valve seat which is made of a sintered Fe alloy and comprises a main layer of a valve seat and a contacting layer, comprises the steps of preparing either a powdery Cu or a powdery material containing Cu in a powdery Fe alloy, forming a green compact body with two green compact body layers, one of which is the main layer and the other of which is the contacting layer, and which are made of the prepared powdery Fe alloy containing Cu, sintering the green compact body. According to the present invention, the infiltration of Cu from the main layer to the contacting layer of the valve seat is not generated as the conventional sintering process for manufacturing the valve seat comprising the two layers without the independent infiltration treatment of Cu, and, therefore, the valve seat obtained of the present invention has an high abrasion resistance without decreasing of a strength of the main layer.

Process for manufacturing valve seat made of sintered FE alloy and valve

A sintered Fe alloy for a valve seat is made of a prepared powdery alloy which comprises C of from 0.3 wt. % to 1.6 wt. %, Cu of from 5 wt. % to 20 wt. %, hard particle of from 5 wt. % to 40 wt. % which consists of at least one species selected from ferroalloy, ceramic and intermetallic compound, and a balance which is a powdery Fe atomizing alloy containing at least one species of from 1 wt. % to 8 wt. % selected from Cr and Mo. The prepared powdery alloy containing the above-mentioned component and content is subject to a press forming process by a compression molding to form a green compact body which is then sintered. The sintered Fe alloy has a high thermal conductivity, a high strength at a high temperature and an excellent abrasion resistance, and, moreover, can be used for a valve seat provided in a high function engine.

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Tochigi, Japan

Hiroshi Oshige