Mitsubishi Heavy Industries Limited

Mao Takei

Toshinari Nishimura

Masaya Kanikawa

Takahiko Hirohata

A valve gear in which corrosion due to a potential difference does not occur and which can reduce the corrosion occurrence even when loads due to microvibrations are given. The valve gear includes a valve stem and a valve bush that slidably supports the valve stem. The valve stem is formed from a forged part made of a Ni-based superalloy and the valve bush is formed from a cast part made of a Ni-based superalloy. The preferable surface roughness of a sliding surface of the valve stem in contact with the valve bush and the preferable surface roughness of a sliding surface of the valve bush in contact with the valve stem is 100 &#x3bc;M or less in units of Rz.

Valve gear having a valve stem and a valve bush

The invention improves reliability of a valve gear in which a cobalt-based alloy is welded by plasma power building up. The valve gear includes a bearinghaving a sliding surface against a valve shaft. The valve gear having a welded layermade of heat-resistant cobalt-based alloy, based on plasma powder building up, formed on the sliding surface against the valve shaft. The welded layerincludes a first welded layerformed on the surface of the bearing, having a dilution ratio of 5 to 25% and a second welded layerformed on the first welded layer, having a dilution ratio of 50% or less of the dilution ratio of the first welded layer. The dilution ratio indicates the penetration amount of the welding metal into the base metal, and is a value obtained by B/A&#xd7;100 (%) wherein A represents the total amount of the welded metal and B represents the amount of the welding metal penetrating into the base metal.

Growing community of inventors

Hyogo, Japan

Mao Takei