Fluid-solid coupling simulation study on fuel leakage and deformation characteristics of precision coupling component in common rail injector and influence of pressure equalizing structure

Abstract

In the foreseeable future, the use of fossil energy is still irreplaceable, makes efficient use of fossil energy and reduce emissions became important topics. Diesel engines have a very high share in the transportation field, and high-pressure common rail system has highly improved the performance of diesel engines. As the most important component of common rail system, the performance of common rail injector directly affects the engine. Precision coupling components are composed of moving parts with very precise clearance fit in the injector. With the wear of parts, fuel leakage of precision coupling components may reach the same level as injection quantity, which will seriously affect the injection pressure actually established, and then affect the power, efficiency, and emission performance of diesel engine. Many researchers have studied fuel leakage of precision coupling components, and put forward different methods to reduce fuel leakage, including improving the machining accuracy and machining annular grooves on parts. However, the wear of parts makes it a high-cost and low-effective method to improve machining accuracy. Besides, researchers have not fully considered the deformation of parts. In this work, fluid-solid coupling simulations were performed to analyze deformation and static fuel leakage characteristics, and to investigate effects of pressure equalizing structure on deformation and leakage of precision coupling component in common-rail injector. Different from the previous researches, the influence of machining the annular groove on the plunger sleeve instead of on the plunger, and influence of coexistence of annular groove and deformation were considered. The results show the deformation characteristics of the parts, the fuel flow characteristics in the gap, and the influence of the annular groove on the fuel leakage. The connection between the deformation of parts and fuel leakage, and potential methods to reduce the leakage are also discussed.