INJECTION SYSTEMS REQUIREMENTS Outlook for electrostatic atomization in automotive applications Rodica A. Baranescu Workshop on Electrostatic Atomization, March 2-4, 2009

Traditional requirements Accurate fuel metering per cycle for load control Accurate fuel metering per cycle for load control Provide vaporization and distribution in combustion space Provide vaporization and distribution in combustion space Provide the mixture in correct proportion under all conditions (start/acceleration/full power) Provide the mixture in correct proportion under all conditions (start/acceleration/full power) Protect sensible components in the injector from damage by deposits in the fuel or by debris Protect sensible components in the injector from damage by deposits in the fuel or by debris

Drivers for Fuel Injection Revolution Stringent emission standards for NOx and particulates, requiring combustion control Stringent emission standards for NOx and particulates, requiring combustion control –Euro V; US 2007; US 2010 Fuel consumption and GHG reduction pressure Fuel consumption and GHG reduction pressure More stringent “sociability” requirements for CI engines More stringent “sociability” requirements for CI engines –driving fun: acceleration, low end torque –improved comfort: low noise, easy start Competition with SI and hybrids (for CI engines) Competition with SI and hybrids (for CI engines) Fuel injection progress seen in both SI and CI engines Fuel injection progress seen in both SI and CI engines

Advanced Requirements for Injection Increase of operating pressure Increase of operating pressure Injection rate control and flexibility Injection rate control and flexibility Multiple injections per cycle (of determined duration and quantity) Multiple injections per cycle (of determined duration and quantity) Electronic control and management of injection process Electronic control and management of injection process

Dimensions of Modern Injection Technology

Challenges for injection systems Reduce injector deposits Reduce injector deposits –High temperature C; 2000 bars; small clearances Reduce oxidation due to heat entrainment in fuel system Reduce oxidation due to heat entrainment in fuel system Improve fuel quality worldwide to provide robustness to modern fuel systems Improve fuel quality worldwide to provide robustness to modern fuel systems Develop new additive technology for increased detergency Develop new additive technology for increased detergency Deal with new fuels (biodiesel) and its poor oxidation stability Deal with new fuels (biodiesel) and its poor oxidation stability Develop new materials and technology for injectors Develop new materials and technology for injectors Develop new software for injection management Develop new software for injection management Strive for global fuel specifications matched to requirements Strive for global fuel specifications matched to requirements

Injection Rate Flexibility Provides: Provides: combustion control combustion control Rate of pressure rise Rate of pressure rise Noise Noise NOx formation NOx formation

Development Targets for Injection Systems Improved nozzle design (including orifices) Improved nozzle design (including orifices) Enhanced metering accuracy Enhanced metering accuracy Increased injection pressure Increased injection pressure Multi injection capability (for combustion control in CI engines) Multi injection capability (for combustion control in CI engines)

Gasoline Manifold Injection (external)

Gasoline Direct Injection (internal)

Gasoline Injection

Common Rail Fuel Injection System from Delphi Common Rail System with Direct Acting Injector, MTZ 10/2008, Volume 69

Common Rail Fuel Injection System from “2000 bar Diesel Common Rail by Bosch for Passenger Cars”, MTZ 10/2008, Volume 69

Common Rail System Features High pressure - independent of injection cycle and engine speed High pressure - independent of injection cycle and engine speed Constant high pressure during injection Constant high pressure during injection Allows more than one injection per cycle Allows more than one injection per cycle Square rate of discharge at full and low load Square rate of discharge at full and low load Penalty in noise and high pressure rise in combustion chamber Penalty in noise and high pressure rise in combustion chamber

Multiple injections patterns 1 pre-injection; 2 main injection; 3 steep rise; 4 boot shape; 5 gradual rise; 6 gradual drop; 7 steep drop; 8 close secondary; 9 late post-injection

Common Rail Fuel Injection System from “Delphi Common Rail System with Direct Acting Injector”, MTZ 10/2008, Volume 69

Piezo Electric Injector Needle hydraulically actuated by piezo stack Needle hydraulically actuated by piezo stack Weight reduced (two fold) Weight reduced (two fold) Up to 5 injections (closed coupled) per cycle Up to 5 injections (closed coupled) per cycle Allows precise injections of small quantities (1mm 3 ) Allows precise injections of small quantities (1mm 3 ) Lower fuel leakage rates ( requires smaller pump) Lower fuel leakage rates ( requires smaller pump)

Conclusions Fuel injection system complexity has increased substantially Fuel injection system complexity has increased substantially Design and packaging is additionally challenging Design and packaging is additionally challenging Lower pressure injection systems seem more suitable to electrostatic atomization Lower pressure injection systems seem more suitable to electrostatic atomization Viscous fuels and liquids and large injection systems seem also suitable to electrostatic charge Viscous fuels and liquids and large injection systems seem also suitable to electrostatic charge Approach is interesting and improved atomization is worthwhile; potential for new hardware designs is significant Approach is interesting and improved atomization is worthwhile; potential for new hardware designs is significant