AEC PRODUCT RANGE

AEC NGVS
AEC ECU
AEC Gas Injector
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AEC Natural Gas Vehicle System (NGVS)

AEC has developed the AEC NGVS which is an electronic fuel injection and engine control system. The electronic AEC NGVS continually measures a wide range of engine operating parameters, including manifold absolute pressure, manifold air temperature, gas temperature and pressure, engine speed and throttle position.

These measurements are taken simultaneously and compared with the various 110 point engine performance tables programmed into the electronic control unit (ECU). A microprocessor performs a complex series of calculations and appropriate adjustments are made to the gas delivery at the inlet ports of each cylinder. Ignition timing is also controlled. This updating is carried out 100 times every second, which is better than once per engine revolution.

A diagram of the AEC NGVS system is shown below:

The features of the AEC NGVS include:

• It is a microprocessor controlled sequential fuel injection system.
  

• Each cylinder is operated at exactly the same air fuel ratio. The engine can therefore be operated at higher power outputs whilst safeguarding it from mechanical damage.

• The system is engine mounted with a minimum of wiring and piping such that change to the engine's original profile is minimised.

• The drive-by-wire system offers neat installation whilst protecting the engine from driver abuse.

• The system is inherently simple in that all previous mechanical complexity has been transferred into software.

• The system has undergone full environmental testing and is built to commercial vehicle standards.

• Fuel efficiency is excellent because of the ability of the ECU to cut gas injection to zero during vehicle overrun and, whilst at idle, a 6 cylinder engine can operate on just 3 cylinders.

• Engine integrity is safeguarded at all times. If overheating should occur, power will automatically be reduced until temperatures return to normal.

• Full data collection is standard. Maximum road speed governing and radio data transmission can also be incorporated.

• The precision of the electronic control system enables low exhaust emission levels to be achieved. The AEC NGVS has satisfied the current Euro 3 draft diesel emission standards for Carbon Monoxide (CO), oxides of Nitrogen (NOx) and non-methane hydrocarbons (THC). These levels can be obtained without the need for exhaust catalytic converters.

• It can be configured to meet or exceed power and torque outputs of the original diesel engine.

AEC Engine Control Unit (ECU)

Processor and Key Software Functions:

• 32 Bit Microcontroller
• 10ms Control Loop Period
• Real Time Clock for date and time stamped Fault and Event Logs
• 8 - 32V
• Multi Point Sequential Fuel Injection
• Fly-by-wire
• Air Density Control
• Closed Loop Exhaust Gas Oxygen Control of a wide Air/Fuel Ratio range of 0.8 - 2.0 or more
• Skip Fire mode for reduced fuel consumption and reduced emissions at idle.
• Configurable Fault reporting
• Engine protection via Configurable De-rate Strategies, Cylinder Cut, Engine Speed governing
• Sophisticated Engine mapping application
• Individual Cylinder mapping for improved emissions
• Pre-emptive load change for accessory eg AC units
• Real Time Fault and Engine Systems Logging

Inputs:

• Hall or VR Crank and CAM inputs
• 4 digital inputs for High/Low Switch, Road Speed, ASR, PWM’s,
• 11 0-5V Analogue inputs that can also be used and digital inputs
• 2 Differential Analogue inputs
• K-Type Thermocouple input for Exhaust Temperature
• Internal Manifold Air Pressure input

Outputs:

• 8 Peak and Hold Injector Outputs
• 8 Ignition Coil Drivers
• 1 H-Bridge Driver for Fly-by-wire manifold Valve Control
• 8 Low side drivers

Communications:

• 1 CAN port
• 1 RS232 port

Diagnostics/Configuration:

• Windows-based application
• Incorporates Engine Configuration, Engine Diagnostics, Engine Mapping
• Fault Log and Event Log Viewing
• Real Time Data Logging
• Engine State Display
  
• Engine Diagnostics tests
  
  • Individual I/O toggling
    
  • Engine Misfire test
    
  • Individual Injector and Ignition testing

AEC Gas Injector

The AEC injector was developed in Australia and is being produced in China for natural gas vehicle systems (NGVS) worldwide.

The advantages of this new injector for OEM applications include:

• Designed specifically for the high flows needed for NGVS multi-point injection
• Designed to functional standards used by the mainstream Tier-1 suppliers and OEMs
• Demonstrates better than 700 million cycles life without any significant change in metering
• Tolerates low lubricity gas supplies
• Insensitive to liquid contaminants in the gas supply, including oil
• Valve bounce is minimised and metering linearity is maximised
• Has high metering accuracy and insensitivity to variations in manufacture and in-field variables. The injector has:
  
  • close control over the static flow independently of injector stroke
    
  • close control over the dynamic flow by 100% inspection and adjustment on the production line
    
• Certification program includes ECE R110 (pending)

Typical operating characteristics using AEC electronics (ECU):

• Typical meter gain at nominal 900 kPa gauge pressure: 5.6 milligrams per millisecond (with virtually no metering offset at 24 volts)
• Typical operating pressure: 600 to 1350 kPa gauge
• Voltage range: 5 to 36 volts.
• Linear metering range (CNG) within 20 millisecond time window: 8 to 110 mg per cycle at nominal gas pressure of 900 kPa gauge
• Variable configurations of the same injector are possible from the same production line. High and low-flow variants can be readily produced each side of the nominal size class outlined above

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