Chemistry: analytical and immunological testing – Including sample preparation – Digestion or removing interfering materials
Reexamination Certificate
1997-06-10
2001-08-28
Ludlow, Jan (Department: 1743)
Chemistry: analytical and immunological testing
Including sample preparation
Digestion or removing interfering materials
C073S060110, C073S114220, C134S113000, C134S16900A, C422S105000, C436S177000
Reexamination Certificate
active
06281020
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of testing the cleanness of the inner surfaces of the parts of a fuel injection system and the parts of a fuel pressure accumulating system, both the systems of which constructing a diesel engine fuel injection system and having contacting parts with a fuel, and the parts of the fuel injection system of which being such as a fuel injection pump, fuel injection nozzle, and fuel injection pipe and the parts of the fuel accumulating system of which being such as a common rail, injection pump, injection nozzle, injection pipe, flow limiter, pressure regulator and feed pipe.
2. Description of the Prior Art
Recently, there is an accelerating trend toward an increase in the pressure of fuel to be supplied to a high pressure fuel injection pipe used typically as the parts of a fuel injection system for a diesel engine as a measure for reducing NOx and black smoke, and this has resulted in a need for fuel injection for an injection period of 1 to 2 msec., at a maximum flow rate of 50 m/sec. and at a high internal pressure in the range from 60 to 1500 bar (peak value).
Such a change in market demands is accompanied by an increased possibility of clogging of an injection nozzle caused by foreign particles such as metal particles which have stuck to the inner surface of a high-pressure fuel injection pipe after floating in the air or entering from the outside, and this can cause a faulty operation of a diesel engine or damage to a fuel pump. Thus, it is an important problem to be solved to improve the cleanness of the inner surface of a high-pressure fuel injection pipe in order to prevent this.
In order to improve the cleanness of the inner surface of a high-pressure fuel injection pipe, however, it is necessary to first establish a method of measurement which makes it possible to properly determine the level of cleanness of a product. Under such circumstances, various methods of testing the cleanness of the inner surface of a high-pressure fuel injection pipe such as methods using a injection pump, hand tester methods, syringe and improved syringe have been proposed by the Society of Automotive Engineers, foreign manufacturers and ISO committees.
However, among the testing methods proposed in the past, both of the injection pump method and hand tester method are unsuitable for the evaluation of a high quality high-pressure fuel injection pipe belonging to the P-class or higher which inherently has less foreign particles because such methods are vulnerable to noises from a pump or nozzle. Further, both of the syringe method and improved syringe method have had a problem in that the extraction of foreign particles present in a high-pressure fuel injection pipe tends to be unsatisfactory, although there is less noise from the measuring system.
Thus, test results obtained according to the testing methods proposed in the past have a low level of reproducibility and also includes variation. As a result, no particular method has been established and put in use yet.
SUMMARY OF THE INVENTION
The inventors have found that variation or the like in the results of cleanness measurement obtained by the various tests on the cleanness of the inner surface of the parts of the fuel injection system as described above is closely related to contamination due to foreign particles in tools and liquids used for testing and conceived that a standardized method of testing the cleanness of the inner surface of the parts of the fuel injection system can be provided by making an improvement on this point.
It is therefore an object of the present invention to provide a method of testing the cleanness of the inner surface of the parts of the fuel injection system which results in less variation in test results and which allows accurate measurement with high reproducibility.
Specifically, according to the present invention, there is provided a method of testing the cleanness of the inner surface of the parts of the fuel injection system characterized in that in testing the cleanness of the inner surface of the parts of the fuel injection system is tested based on foreign particles collected by a filter for filtering a measurement liquid obtained by washing the inner circumferential surface of the parts of the fuel injection system, at least the part of a group of measuring apparatuses used for testing the cleanness of the inner surface of the parts of the fuel injection system 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.
Further, in testing the cleanness of the inner surface of the parts of the fuel injection system, it is preferable to wash the part of the tools used for preparing the measuring liquid for the testing of the cleanness of the inner surface of the parts of the fuel injection system that is in contact with the measuring liquid is washed in advance using the washing solution comprising a solvent for dissolving foreign particles.
In addition, the solvent for dissolving foreign particles is preferably an acid, alkali or organic solvent, and such cleaning utilizing the solvent for dissolving foreign particles is preferably repeated a plurality of times utilizing different kinds of solvents or the same kind of solvent.
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Casella Anthony J.
Hespos Gerald E.
Ludlow Jan
Porco Michael J.
Usui Kokusai Sangyo Kaisha Limited
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