Patent ID: 6382942
Filing Date: 2002-05-07
Classification: F04C

Abstract:
An internal gear oil pump made of Al alloys, comprising a casing having a gear compartment, a drive gear, and a driven gear as structural members,(a) said casing comprising an Al-alloy casting, (b) said drive gear and said driven gear comprising an Alâ€”Si alloy powder hot plastic working material, (c) the hot plastic working material comprising an Alâ€”Si alloy having a structure in which unit crystal phases are dispersed in a base matrix at 10 to 40 area percent by observation of the structure thereof using an optical microscope, the unit crystal phases being harder than the base matrix, (d) the base matrix comprising an Alâ€”Si alloy comprising, on a weight basis, 10% to 18% Si, 4% to 8% Fe, 1% to 3% Ni, 1% to 3% Cr, the balance being Al and incidental impurities, the alloy having a structure in which ultrafine grains of intermetallic compounds and Si are dispersed in the base matrix, and (e) the unit crystal phases comprising an Alâ€”Si alloy comprising, on a weight basis, 25% to 40% Si, 1% to 3% Fe, 2% to 6% Ni, 0.3% to 2% Cr, and the balance being Al and incidental impurities, the alloy having a structure in which ultrafine grains of intermetallic compounds and Si, and primary Si crystal grains are dispersed in the matrix of the unit crystal phases.