Solenoid-operated diesel injectors for low-viscosity liquid and gaseous fuels

Abstract

Alternative fuels such as liquid dimethyl ether have low viscosity that result in fuel leakage in diesel components, while natural gas and hydrogen are too compressible for diesel pressure operated injection. A new solenoid-operated injector design for diesel alternative fuels is described. Less force is required to open the injector because of the pressure-balanced design by having the pressure across the needle guide the same. A pulling rod is attached between the electrical solenoid core and needle guide. Activating the solenoid produces the electromagnetic force to pull open the injector needle. Circulation of the fuel through the common rail housing the solenoids is used to prevent the coils from excessive heat that tends to reduce the solenoid force. On injector closing, the elasticity of the pulling rod provides relative motion damping so that the core's inertia force is reduced as it is transferred to the needle. This results in lower impact forces between the needle and its seat and lessens their wear. Also, the magnitude of the needle seat bounce is attenuated and results in less post-injection and emission pollutants. The study of needle-to-seat impact forces has been modelled for computer simulation and has been verified with experiments.