US 8,167,270 B2Granted

Valve gear with a bearing having a sliding surface against a valve shaft

AssigneeMitsubishi Heavy Industries, Ltd.

InventorsMao Takei, Toshinari Nishimura, Takahiko Hirohata, Masaya Kanikawa

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Abstract

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 bearing 2 having a sliding surface against a valve shaft 1. The valve gear having a welded layer 12 made of heat-resistant cobalt-based alloy, based on plasma powder building up, formed on the sliding surface against the valve shaft 1. The welded layer 12 includes a first welded layer 12a formed on the surface of the bearing 2, having a dilution ratio of 5 to 25% and a second welded layer 12b formed on the first welded layer 12a, having a dilution ratio of 50% or less of the dilution ratio of the first welded layer 12a. The dilution ratio indicates the penetration amount of the welding metal into the base metal, and is a value obtained by B/A×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.

Claims4

Dependent claims

A valve gear comprising a bearing having a sliding surface against

a valve shaft, wherein:
the bearing has a plasma powder building-up welded layer (X) made of a heat-resistant cobalt-based alloy on the sliding surface against the valve shaft;
the valve shaft has a plasma powder building-up welded layer (Y) made of a heat-resistant cobalt-based alloy on a sliding surface thereof against the bearing;
the welded layer (X) formed on the bearing comprises:
a first welded layer formed on the surface of the bearing, having a dilution ratio of 15 to 25%;
and
a second welded layer formed on the first welded layer, having a dilution ratio of 50% or less of the dilution ratio of the first welded layer;
and
the welded layer (Y) formed on the valve shaft comprises:
a third welded layer formed on the surface of the valve shaft, having a dilution ratio of 15 to 25%;
and
a fourth welded layer formed on the third welded layer, having a dilution ratio of 50% or less of the dilution ratio of the third welded layer.

9 more elements

Dependencies are inferred from the claim text.