Scuffing Failure Due to an Abrasive Contaminant and Filter Suitability in High Pressure Injection Fuel System

Abstract

The field studies have revealed that there is an unprecedented high failure rate of rotary diesel fuel injection pump (RDFIP). The presence of rigid abrasive contaminant between the plunger and sleeve of hydraulic head assembly of RDFIP causes scuffing failure. The abrasive contaminant is modeled as a spherically shaped rigid particle. The contaminant is envisioned to penetrate into the sleeve while positioning itself in rubbing contact with the plunger. Excessive temperature rise known as flash temperature between the particle-plunger interface is used as an indication of whether scuffing would take place. Flash temperature is determined by incorporating operating speed of pump, particle size, minimum film thickness, fuel properties, thermomechanical and surface properties of plunger and sleeve. Thermomechanical properties are determined through material composition of plunger and sleeve by spectroscopic techniques. Coordinate measuring machine is used to determine the radial clearance between the plunger and sleeve. Three high-pressure injection pumps are taken as case study for obtaining experimental data. This experimental data is used as an input in our theoretical model for the determination of flash temperature duly analyzing partial and diametric penetration of the abrasive contaminant. The model uses flash temperature in conjunction with the material properties to determine the critical particle size that may result in scuffing failure. The exact rating of fuel filter based on the critical particle size of the contaminant producing scuffing failure in the plunger and sleeve of hydraulic head assembly of RDFIP is also determined. The range of critical particle size initiating significant abrasive wear is determined and validated with the experimental results available in literature.