Man B&w Diesel A/s

Man Diesel & Turbo, Filial Af Man Diesel & Turbo Se. Tyskland

Harro Andreas Hoeg

Christian Skaaning

An exhaust valve for an internal combustion engine comprises a valve disc having a first side () and a second side (), a valve stem extending from the first side of the valve disc, and an annular valve seat area () located at the first side of the valve disc. The annular valve seat area () is of a nickel-base alloy or a chromium-base alloy and has a valve seat surface. The annular valve seat area has at least a first annular portion () located in between two second annular portions (). The first annular portion has lower hardness than the two second annular portions.

Exhaust valve for an internal combustion engine, and a method of strengthening an annular valve seat area in an exhaust valve

An exhaust valve for an internal combustion engine comprises a movable spindle with a valve disc which on its upper surface has an annular seat area of a material different from the base material of the valve disc. In the closed position of the valve the seat area abuts a corresponding scat area on a stationary valve member. The seat area on the upper surface of the valve disc is made of a material which has a yield strength (R ) of at least 1000 MPa at a temperature of approximately 20&deg; C.

Exhaust valve for an internal combustion engine

An exhaust valve for an internal combustion engine including a movable spindle with a valve disc which on its upper surface has an annular seat are of a material different from the base material of the valve disc. In the closed position of the valve the seat area abuts a corresponding seat area on a stationary valve member. The seat area on the upper surface of the valve disc is made of a material which has a yield strength of at least 1000 Mpa at a temperature of approximately 20&deg; C.

An exhaust valve for an internal combustion engine including a movable spindle with a valve disc of a nickel-based alloy which also constitutes an annular seat area at the upper surface of the valve disc. The seat area abuts a corresponding seat area on a stationary valve member in the closed position of the valve. At manufacturing, the seat area of the valve disc is subjected to a thermo-mechanical deformation process at a temperature lower than or around the recrystallization temperature of the alloy. The seat area on the upper surface of the valve disc has been given dent mark preventing properties in the form of a yield strength of at least 1000 MPa at a temperature of approximately 20&deg; C. by means of the thermo-mechanical deformation process and possibly a yield strength increasing heat treatment.

A wall member is on its side facing a combustion chamber provided with a hot-corrosion-resistant material made from a particulate starting material of an alloy containing nickel and chromium which by a HIP process has been unified to a coherent material substantially without melting the starting material. In terms of percent by weight the corrosion-resistant material comprises from 38 to 75% Cr, at the most 0.15% C, at the most 1.5% Si, at the most 1.0% Mn, at the most 0.2% B, at the most 5.0% Fe, at the most 1.0% Mg, at the most 2.5% Al, at the most 2.0% Ti, at the most 8.0% Co, at the most 3.0% Nb and a balance of Ni, the aggregate contents of Al and Ti amounting at the most to 4.0%, and the aggregate contents of Fe and Co amounting at the most to 8.0%, and the aggregate contents of Ni and Co amounting at the least to 25%. The corrosion-resistant material has a hardness of less than 310 HV measured at approximately 20&deg; C. after the material has been heated to a temperature within the range of 550-850&deg; C. for more than 400 hours.

Movable wall member in the form of an exhaust valve spindle or a piston in an internal combustion engine

A cylinder member for an internal combustion engine such as a valve, piston, cylinder liner or seat portion. The member has a welded high temperature corrosion resistant facing alloy with a hardness increased by use of a precipitation hardening mechanism based on a solid state phase transformation. The facing alloy has a temperature of activation of the precipitation hardening mechanism that is above the operating temperature of the alloy. The participation hardening mechanism acts so slowly that the alloy has not hardened at welding on the cylinder member Hardening occurs during a subsequent heat treatment at a temperature higher than the activation temperature for the participation hardening mechanism.

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Allerød, Denmark

Harro Andreas Hoeg