New low cost common rail system with zero static leakage
Fuel economy is more and more important for diesel engines. Emission levels become more and more stringent. To fulfill stringent emission levels, a common rail system is mandatory. Fuel economy yields for a zero static leakage common rail system. Additional to this two requirements, manufacturing costs should be as low as possible. According to this requirements a common rail system, mainly consisting fuel injector and high pressure pump, was designed, built and tested. Because of costs, the injector uses a solenoid actuator. As usual, the solenoid is about 20 mm in diameter. For smaller engines the slim body of the injector does not allow to place the solenoid near the injection nozzle. To avoid static leakage, the injector has a central fuel bore only. This means the injector needle is completely surrounded by pressurized fuel. The needle is very long to reach the on the top placed solenoid. This length can cause friction problems due to misalignment caused by manufacturing imperfections. To enhance the acceptance of manufacturing imperfections, a flexible needle was invented. This invention keeps manufacturing costs low and minimizes injector to injector deviations. To keep costs regarding high pressure fuel pump as low as possible, the pump is fuel lubricated. Fuel lubrication additionally minimizes the over all costs of the whole engine. The pump has a very simple crank drive with a so called race ring. This race ring is sitting on the eccentric part of the crankshaft. The plunger feet is rolling directly on this race ring. Except for the plunger spring, there is no need for an additional part transforming revolutions into strokes. The pump owns two plungers. This is the minimum number of plunger to make sure the pump is capable of delivering fuel all the time. The pump is designed for high speed, e. g. 4000 rpm. If the engine builder uses this potential, the pump can be designed smaller and with less weight, which also improves fuel economy of the whole engine. High speed pumps also cause smaller pressure fluctuations. A further advantage. The tests and measurements of the components showed a good injection behavior for the injector and a high efficiency regarding high pressure fuel pump.
Raphael Fuechslin
Lafei,Switzerland
国际会议
上海
英文
1-9
2013-05-13（万方平台首次上网日期，不代表论文的发表时间）