• near-zero emissions of particulate matter
  
  
• 20% less greenhouse gas emissions (mainly carbon dioxide) than equivalent diesel engines
  
  
• 25% increased fuel efficiency over current spark-ignited natural gas engines
  
  
• high thermal efficiency and improved driving range (more miles per gallon) compared to current spark-ignited natural gas engines
  
  

Technology Description
CNG-DI relies on late-cycle high-pressure injection of a gaseous fuel such as natural gas into the combustion chamber of an internal combustion engine in much the same fashion as diesel fuel. Just like in the diesel cycle, the natural gas is injected near the end of the compression stroke. Natural gas has a higher ignition temperature than diesel (1,000° C vs. 500° C) and will not easily ignite at the temperatures and pressures in the combustion chamber of a normal diesel engine. To ignite the natural gas, a hot surface, such as a ceramic-tipped glow plug, is used in the engine.

Our electronic fuel injectors deliver the natural gas, and the hot surface ignition system using the glow plug provides optimal ignition. Emissions are drastically reduced because of the natural gas, but diesel-cycle diffusion combustion retains the power, torque, and efficiency of the diesel engine. Our catalyst equipped, dedicated, monofuel natural gas engines have near-zero emissions of particulate matter.

CNG-DI technology achieves true natural gas diesel cycle operation. This combination of natural gas and high efficiency operation results in a significant carbon dioxide reduction benefit when compared to diesel and spark-ignited natural gas vehicles.


How CNG-DI works

The hot surface within the ignition system is a ceramic tipped glow plug operating between 1,200°C and 1,300°C. This is surrounded by a closed shield to ensure that ignition occurs in a robust manner, and that all the fuel jets are ignited. The ignition system is controlled to ensure that correct glow plug temperature is maintained at all times, providing optimum ignition performance and minimum glow plug temperature.