Direct injection provides a precisely metered charge to the cylinder that allows beneficial engine design and operating changes—like a higher compression ratio—to be employed on the engine. GDI fundamentally promotes more stable combustion giving the customer better performance and lower hydrocarbon and carbon dioxide emissions with no sacrifice in engine performance.

The technology also offers multi-fuel capabilities for emerging E85 applications.

—Mike Crane, Siemens VDO North American Director of Powertrain Gasoline Systems

Siemens VDO currently is pursuing a dual strategy of solenoid-actuated and piezo-actuated direct injection to address the needs of diverse customer market segments and models. The core components of both these gasoline direct-injection systems are the injectors, the EMS 2 engine management system with corresponding software and a high-pressure fuel pump.

Piezo Direct Injection (PDI)—the high-end solution—offers the customer the greatest possible fuel savings throughout an extended engine operating range by facilitating stable lean combustion in stratified operation, according to Crane. Compared conventional port injection, PDI can reduce fuel consumption by up to 20%, depending on the total level of system integration, including engine downsizing.

Solenoid Direct Injection (SDI) system is a cost-effective solution offering significant opportunities to save fuel, reduce emissions and boost torque at lower engine speeds compared to port injection systems.

The injector delivers the versatility required for variable injection through enhanced linearity, very fast opening and closing times and varying nozzle designs for swirl or multi-stream spray geometry for optimal adaptation to specific engine requirements.

A new high-pressure fuel pump offer greater flow control accuracy and requires less power from the engine to operate compared to competitive pumps. The pump generates fuel pressures of up to 20 MPa (200 bar) and works on the transfer principle. The moving parts are contained in an oil chamber separated from the fuel system by a stainless-steel diaphragm to minimize the drive torque, while simultaneously preventing oil contamination of the fuel.

Siemens VDO competitor Bosch is providing the GDI systems for both Mercedes and BMW/PSA. (Earlier post.)