FUEL INJECTION SYSTEMS WITH A FOCUS ON FUEL

Overview Fuel Injection Systems � Speed Density � EFI Fuel Injector Design Fuel Atomization

Speed Density Fuel Injection Sys. Fuel Flow Path: � Air Flow Path � Pump

EFI System Fuel Flow Path � Air Flow Path � Same as Speed Density

Fuel Injector Electromagnetically actuated valve � Can cycle several times a second Controlled by

Fuel Atomization is a function of: � Fuel injector geometry � Fuel jet velocity

Swirl Nozzle Injectors Multiple types, one pictured from patent 6029913 � Filed by Cummins

Electrospray Injection Installed Electrode: � Downstream fuel injector � Upstream orifice Benefits � Reduces

Electrospray Experimental Results 0 KV Fuel jet No jet 30 KV Wider more homogeno

Electrospray Issues Charge To Mass Ratio (of droplet) � � � Charge Used in

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FUEL INJECTION SYSTEMS WITH A FOCUS ON FUEL ATOMIZATION By: David Shamrell

Overview Fuel Injection Systems � Speed Density � EFI Fuel Injector Design Fuel Atomization � Swirl Injectors � Electrospray

Speed Density Fuel Injection Sys. Fuel Flow Path: � Air Flow Path � Pump → Filter → Regulator → Branch Lines → Injector. Air Filter → Throttle Plate → Intake Manifold Determines Air Flow Via: � � � Engine Speed Manifold Pressure Air Temperature

EFI System Fuel Flow Path � Air Flow Path � Same as Speed Density Air Filter → Air Flow Sensor → Throttle Plate→ Intake Manifold Determine Air Flow Via: Measured Air Flow � Engine Speed � Air Flow Sensor

Fuel Injector Electromagnetically actuated valve � Can cycle several times a second Controlled by Electronic Control Unit (ECU) � Nozzle design affect atomization Needle helps minimize dribble (secondary injection)

Fuel Atomization is a function of: � Fuel injector geometry � Fuel jet velocity Function � Spray type (turbulent or laminar) Function � Fuel of fuel system pressure of nozzle type (Swirl, etc) delivery temperature � Fuel electrical charge

Swirl Nozzle Injectors Multiple types, one pictured from patent 6029913 � Filed by Cummins Engine Company 1998 6 curvilinear spray holes 90 degree curvature orientation “flow through tangential flow path causing rapid spreading and breakup of fuel jet spray upon exiting spray hole”

Electrospray Injection Installed Electrode: � Downstream fuel injector � Upstream orifice Benefits � Reduces surface tension of liquid � Shortens breakup length � Enlarges the cone angle of the spray

Electrospray Experimental Results 0 KV Fuel jet No jet 30 KV Wider more homogeno us spray

Electrospray Issues Charge To Mass Ratio (of droplet) � � � Charge Used in Experimental = 30 KV � Inversely proportional to droplet size Step increase around 20µm (droplet diameter) Modern techniques w/out electrode can achieve 10µm Hard to obtain in a mobile platform Injection velocity vs. charge (Competing Factors) � Charge imparted is a function of time � Slower velocity = more charge However atomization is proportional to injection velocity Thus slower velocity = less atomization