US 6,281,020 B1Granted

Method of testing cleanness of inner surfaces of the parts of a fuel injection system

AssigneeUsui Kokusai Sangyo Kaisha Limited

InventorMasayoshi Usui

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Abstract

The present invention provides a method of testing the cleanness of the inner surface of a high-pressure fuel injection pipe in which the cleanness of the inner surface of a high-pressure fuel injection pipe can be accurately measured with less variation and high reproducibility. In testing the cleanness of the inner surface of a high-pressure fuel injection pipe based on foreign particles collected by a filter for filtering a measuring liquid obtained by washing the inner circumferential surface of the high-pressure fuel injection pipe, at least the part of a group of measuring apparatuses used for testing the cleanness of the inner surface of the high-pressure fuel injection pipe that is in contact with the measuring liquid is washed using a washing solution comprising a solvent for dissolving foreign particles prior to the testing of cleanness.

Claims14

Dependent claims

A method for testing cleanness of an inner surface of a part of a fuel injection system, wherein said testing of cleanness includes the steps of washing the inner surface of said part of the fuel injection system with a measuring liquid, filtering the measuring liquid with a filter to remove foreign particles therefrom, and determining the cleanness of the inner surface of said part based on the foreign particles collected by said filter, and wherein tools are provided for preparing said measuring liquid, and wherein the measuring liquid is selectively handled by measuring apparatuses during said testing of cleanness, the improvement comprises the steps of:

washing portions of said measuring apparatuses that come into contact with said measuring liquid using a washing solution comprising a first solvent for dissolving foreign particles prior to the testing of cleanness;
and
prior to the testing of cleanness, washing the portions of said tools that come into contact with said measuring liquid using a second washing solution comprising a second solvent for dissolving foreign particles prior to the preparation of said measuring liquid;
wherein said first solvent is phosphoric acid and oxalic acid-hydrogen peroxide for dissolving iron or organic foreign particles, caustic soda for dissolving iron foreign particles, or an alcohol for dissolving fats and fatty oils or said second solvent is phosphoric acid and oxalic acid-hydrogen peroxide for dissolving iron or organic foreign particles, caustic soda for dissolving iron foreign particles, or an alcohol for dissolving fats and fatty oils.

1 more element

Dependencies are inferred from the claim text.