Bosch leads consortium to develop direct injection systems for NGVs

Bosch leads consortium to develop direct injection systems for NGVs

Compared with present systems that use manifold gas injection, direct injection could deliver as much as 60% more torque at low rpm, and offer the prospect of an even more dynamic driving experience in the CNG cars of the future. However, there is still no technology for directly injecting natural gas into the combustion chamber. In the Direct4Gas project, supported by German government, researchers now want to develop a direct injection system for monovalent engines, or engines that run exclusively on CNG.

Today’s NGVs are generally bivalent, running on gasoline and CNG with engines designed for gasoline direct injection. For CNG operation, they are fitted with an additional manifold injection system for methane. “The problem with this configuration is that neither the combustion process nor the values for efficiency and emissions can be optimized. For this to happen, the CNG – like the gasoline – needs to be injected directly into the combustion chamber,” said Andreas Birkefeld, project leader from Robert Bosch GmbH. Because methane behaves differently from gasoline when injected directly, it is important to optimize the combustion process for methane.

The Direct4Gas researchers will design samples of a direct injector that satisfies much higher standards than the manifold injection valves used up to now. It will have to be especially robust, gas-tight, and reliable, and meter the CNG very precisely. Modifications to the engine itself are to be kept to a minimum, so that the industry can continue using the same components as for gasoline engines. The project team will equip experimental gas engines with the newly developed injector, and test it in the laboratory and in vehicles.

The long-term objective of the consortium of automotive suppliers and automakers is to generate the conditions needed for making the technology ready for production, and the project is an important step toward this goal. The consortium led by Robert Bosch GmbH also includes Daimler AG and the Research Institute of Automotive Engineering and Vehicle Engines Stuttgart (FKFS).


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