Bosch Leads Research Project for Direct-Injection CNG Engines


Robert Bosch GmbH has announced it is leading a government-funded research project in Germany to develop a direct-injection system for dedicated compressed natural gas (CNG) car engines. Consortium partners of the Direct4Gas project include Daimler AG and the Research Institute of Automotive Engineering and Vehicle Engines Stuttgart (FKFS). Umicore AG & Co. KG is an associated partner.

Bosch says that compared with present systems that use manifold gas injection, a CNG direct-injection system 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.

According to the company, today's CNG cars are generally bi-fuel, 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,” says Dr. Andreas Birkefeld, the 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, he adds.

Bosch claims the Direct4Gas researchers and engineers 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, as well as meter the CNG very precisely, the company says. 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. Researchers will also examine mixture formation, ignition, and exhaust-gas treatment and develop specific solutions.

The long-term objective of the consortium of automotive suppliers and automakers is to create the conditions needed for making the technology ready for production.

Following a resolution of the German Bundestag, Direct4Gas is supported with EUR 3.8 million from the Federal Ministry for Economic Affairs and Energy as part of the “Increasing vehicle powertrain efficiency” initiative. By 2020, newly registered vehicles in the European Union will not be permitted to emit more than 95 grams of CO2 per kilometer on average. By 2025, this limit could be even lower. Bosch says efficient CNG vehicles can help meet these emissions standards.

The Direct4Gas project started in January and will run until the end of 2017.

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