Design Of A Throttleless Engine For A F 1502

Design of a Throttleless Engine for a F-150 Truck

Rebekah Achtenberg, Terrence Tabata, Brent Timmerman

Engine SpecificationsFord F-150 Engine Specifications

Engine Type 5.4L

Engine Electronics Engine Ignition System, EEC-V Computer

Displacement 330 CID

Horsepower (SAE net@RPM) 310@5000

Torque (lb.-ft.@RPM) 365@3500

Compression Ratio 9.8:1

Bore x Stroke (in.) 3.55x4.17

Main Bearings 5

Valve lifters Hydraulic, roller finger

Fuel Delivery Sequential multi-port electronic injection

Recommended Fuel Unleaded/E-85

Fuel Economy 4x2 14 City/20 Hwy

Exhaust Stainless Steel

Transmission type Electronic 6-speed automatic with overdrive

Engine Block Material Cast Iron

Cylinder Head Material Aluminum

What is a Throttle?The throttle controls

the amount of air that enters the cylinder

It is associated with pumping losses

Pumping LossesPumping losses account for about 15% of the

Brake Power.In our vehicle, we found that there is about

35kW of power that is removed from the brake power due to pumping losses.

Throttle losses are big factor in pumping losses

Methods of Operating ThrottlessExhaust Gas Recirculation

EGR cannot be used alone in throttleless operation, need other methods that also reduce pumping losses

TurbochargingVariable Valve Timing

The biggest factor in throttleless operation

Exhaust Valve OpeningVariable Valve Timing SystemFor High Speeds

The timing for the exhaust valve opening should begin before the bottom dead center (50-60 degrees BBDC)

This reduces the pumping work done by the piston to expel the combustion products

For Low SpeedsThe timing for the exhaust valve opening

should begin just after the bottom dead center

Exhaust Valve ClosingTiming is critical because at full loads there

should be no exhaust gas left in the cylinderHowever at partial loads it is desirable to

have some exhaust gases left in the cylinderi.e. EGR

Exhaust valve closing should occur right at top dead center or just after (5-15 degrees ATDC)

Intake Valve OpeningTiming for the intake valve opening is critical

If it is open before top dead center exhaust gases could flow into the intake manifold

If it is open too late the air/fuel ratio in the cylinder could be restricted and could cause a drop in pressure as the piston descends Also can reduce the volumetric efficiency

Typically 0-10 degrees BTDC

Intake Valve ClosingTiming for the intake valve closing affects the

amount of air/fuel ratio in the cylinderThe greatest ratio will result in the largest

torqueAs the engine speed increased the timing

moves farther after bottom dead centerTypically 50-60 degrees ABDC

Methods of Variable Valve Timing (VVT)Phase Changing Systems

In order to advance or retard the timing of the engine valves, a phase changing system changes the timing of the camshaft in relation to the crankshaft. If this system is applied to an engine with a single camshaft then all valve events are shifted by the same amount

Phase change systems cannot change the duration of the valve events and do not have an effect on the valve peak timing.

Methods of VVT Continued Profile Switching Systems

Unlike the Phase Changing System, the Profile Switching System has the ability to independently change the valve timing and valve peak lift.

This system has two different camshaft profiles and switches between them usually at some specified engine speed. This system can be used on one or both shafts..

By being able to change the valve event, lift, and duration, this system allows for the ability to have a high power output while complying with lower emission legislation.

Methods of VVT ContinuedVariable Event Timing Systems

The Variable Event Timing System almost combines the Profile Switching and Phase Change System. It can not only change the phase, but also change the duration of the valve events. The Variable Event Timing System cannot change the peak valve lift.

These systems are not only optimized for engine speed, but also optimized for variable loads and can be controlled to any setting between two extremes.

Methods of VVT ContinuedVariable Lift Systems

There are two types of Variable Lift Systems that are currently being researched and developed One type “scales” the valve lift such that its opening

duration is unchanged The second type of valve lift system “truncates”

such that the valve opening duration reduces as lift reduces

A major benefit of using this system is the potential of throttling the cylinder by reducing the intake valve lift

Methods of VVT ContinuedElectro-magnetic Valve Actuation Systems

The idea is that IVO, IVC, EVO, EVC, and valve lift could all be controlled by an engine management system

Electro-magnetic Valve Actuation Systems have the greatest potential to be able to optimize all of the engine valve events

VVT System Chosen for the TruckThe Ford truck has 3 valves – 2 intake and 1

exhaust.At lower speeds, only one intake valve would

be opened.At medium speeds, one intake valve would be

opened and the other valve would only be partially opened. This allows for better swirl and thus better

combustion.At high speeds, both intake valves would be

open to allow for maximum air flow.

Throttleless System Chosen for the TruckCamshaft

On the camshaft, there will be three lobes. Two for low speed RPM and one for high speed

Lobes are connected by a rockerLobe Switching Mechanism

At specified speed stored in the ECU, an electric signal is sent to open a spool valve. The spool directs oil pressure to a mechanical sliding pin. The pin locks the valve actuator to the high speed cam lobe.

VVT System similar to Chosen system

Throttleless System Chosen for the TruckSince throttle not only controls how much air is being

inducted into the cylinder, it also notifies the CPU (in modern cars) of how much fuel is needed based on the throttles position. Thus a modified algorithm will need to be programmed into the CPU to ensure that the proper amount of fuel is being injected into the cylinder.

In a normal engine the throttle body setting is dominant and controls the amount of fuel and the valve lift. In the throttleless engine neither the fuel nor the valve lift is dominant over the other and the fuel and valve lift can adjust to each other. The fuel system and variable lift are controlled using parallel signals. This will allow much finer control of the engine and its characteristics

Throttleless System Chosen for the TruckDifferent spray patterns can be created by

increasing the pressure of fuel rail. The duty cycle of the injectors can also be adjusted to give different spray effe.

Adjusting the pressure of the injector can also change the amount of atomization and the flow rate of the fuel

ConclusionsFurther development of VVT systems is key

for throttlelessFine tuning other components of the engine,

such as the fuel injector is also keyDecreases the pumping losses

Any Questions?