The Use of Plastic Cold Flow in the Development of an Externally Connected Transducer for Recording Pressure-Time Histories of Diesel Fuel Injection Phenomena and Its Application in Fault Diagnosis

An investigation of possible methods for obtaining a pressure-time history of the diesel fuel injection cycle was conducted, with the object of producing a rugged externally connected pressure transducer. A resistance technique that discriminates against characteristics not directly associated with dynamic pressure was developed and the resulting principles incorporated into the design of a compact transducer [1]. In order to eliminate the necessity of cementing a resistance element directly to the high-pressure line, a technique using the cold flow of cured resin held captive in a steel enclosure was developed. This has resulted in an instrument of equal sensitivity and fidelity which may be installed in the field by personnel without specialized training. Diagnostic techniques applied to the analysis of diesel fuel injection health are described that are considered to have practical field application, using an externally connected transducer. No numerical measure is required, the method being based on comparison of fault signatures with a healthy master. The signature is considered to contain a definite quantity of criteria evaluated by a defined series of qualities resulting in a less nebulous approach than that of random comparison by superimposure. Nine of the most common diesel fuel injection faults are induced, checked for repeatability, and used as representative examples to illustrate the method.