Cold Performance Challenges with CNG PFI Injectors 2013-01-0863

Compressed Natural Gas (CNG) is gaining popularity as a viable alternate transportation fuel in many regions of the world. Injectors capable of delivering pressurized gaseous fuels have been developed for this emerging vehicular market segment. CNG fuel injectors must be designed to be compatible and durable with a very low lubricity gaseous fuel to meet automotive OEM life expectancy standards. Traditional gasoline injectors utilize a “hard/hard” sealing configuration, in which both the valve and seat are constructed out of hard metals. When properly lubricated with liquid fuels, these valves can meet vehicular injector leak and flow durability requirements. However, metal valves operating without lubrication can experience excessive wear, which leads to unacceptable levels of gas leakage and flow shifts. The use of elastomer-to-metal sealing surfaces minimizes leakage, but may cause cold ambient operation challenges. In this paper we will provide an overview of a compressed natural gas port fuel injector and associated test results for meeting both durability and cold performance challenges.