SBIR-STTR Award

The Army uses JP-8 fuel for both its tactical and non-tactical, diesel powered vehicles. Some of the commercial engines used by the Army employ high pressure, common rail fuel injection systems to lower exhaust emissions, especially particulates. Modern common rail injection systems produce pressures of 1500 to 2200 bar. These systems are designed to run on ultra-low sulfur diesel fuel that contains special lubricity additives (usually fatty acids) to reduce wear and scuffing. JP-8 fuel does not contain these important additives. Therefore, to achieve acceptable fuel system life, special fuel filters have been devised that meter a lubricity additive to the fuel system. The use of these filters is undesirable from a field logistics perspective. We propose to eliminate the need for "lubricity filters" and additives by redesign of the common rail pump. We have developed materials pairs and other proprietary methods that significantly reduce the wear of high pressure common rail pumps. In phase 1, we propose to conduct a bench durability test on a common rail fuel pump (Cummins ISL) to define which components have unacceptable wear. We will then develop a design proposal that suggests changes to reduce wear without the use of fuel additives.

Keywords:
Jp-8 Fuel Properties, High Sulfar Fuel, Fuel Additives, Military Diesel Engines,High Pressure Common Rail Pump

Development of the Bosch CP-3 Common Rail Pump for JP-8 Fuel. In Phase 1, tests showed that the CP-3 pump had high wear after only 500 hrs. of testing using JP-8 fuel. This wear is caused by the very low viscosity of the fuel, and the lack of effective anti-wear additives in the fuel. The primary problems identified are: (1) tappet wear, (2) plunger wear (contact button), (3) bearing cavitation, (4) Oldham drive wear, (5) fuel seal and shaft wear and (6) inlet valve and seat wear. The solution to these problems will include changes in basic design geometry, materials and heat treatment. Although our proposal will describe detailed design proposals, the final solutions will stem from engineering analysis. The project is divided into three separate phases: (1) Design, analysis and manufacture of a prototype and a 500 hr accelerated proof test. (2) Deficiencies will be corrected and a 2nd. prototype will be built and tested (500 hrs). (3) Any remaining problems will be corrected and a 3rd prototype will be built. This final prototype will be tested for 1000 hrs(with a 500 hr inspection)under accelerated test conditions. The pump will be inspected and a final report will be written.

Keywords:
Common Rail Pump, Wear Reduction, Jp-8 Fuel