Alternative Fuel Electronic Control Unit

Alternative Fuel Electronic Control Unit

Project brief:
Develop an affordable electronically controlled alternative fuel conversion system able to interface with modern electronically fuel injected vehicles with on-board diagnostics (OBD-II).
Requirements:
• Flexible fuel metering system, for gaseous fuels such as CNG, LPG and hydrogen
• PC interface
• Software configurable and remote firmware update
• On-board diagnostics of gas system, fault detection, fail-safe and datalogging
• Seamless interface with vehicle sensors
• Interface and communication with OEM electronic control unit via OBD CAN interface
• Simple installation process including software configuration
Design work:
The design work was split into four stages, market research, conceptualization, prototype development and design for manufacture. The market research stage required investigation of current technologies available in the conversion market: analyzing the respective strength and weakness. Investigation of regulatory requirements and certification requirements and knowledge gathering from vehicle owners and conversion system installers to understand the problems associated with current technologies.
Results from the market research stage were collated to develop several concepts that combined the aspects of simple installation and commissioning with advanced diagnostic features and adaptive
fuelling control. Prototype development require CAD design and computation fluid dynamic analysis on the electromechanical fuel metering unit. Electronic circuit design to interface with existing vehicle sensors such a throttle position sensor, coolant temperature sensor and oxygen sensor ensuring that no impact was made on signal integrity. Firmware development to extract fuelling information from vehicle sensors and translate the information into fuelling requirements for control of the metering device. Further firmware development entailed building fault detection routines and adaptive fuelling algorithms. An isolated communication module (USB-RS485) was also developed to interface between the PC and electronic controller.
During the prototype development phase tests were conducted on several vehicle platforms to verify system modularity. Design form manufacture included all manufacturing files and documentation for circuit board manufacturing, assembly and testing. Wiring harness design documents, wire specification and connection sourcing and specification. A website base encrypted firmware download facility was also set in place for remote firmware uploading.
Outcome:
The outcome of the project was the development of a complete alternative fuel conversion solution specifically designed for the target market of South East Asia and Latin America.
Key features:
• Complete systems design including electronic controller, wiring harness, PC interface
software, user switch and isolated PC interface unit.
• Electronic alternative fuel conversion system for vehicles with up to 4 cylinders
• Customised PC communication protocol
• Peak-hold (4-1A) low impedance coil drivers with fault detection
• On-board diagnostics off all alternative fuel system sensors and actuators
• Freeze frame data and 10sec recorded information prior to system fault.
• Communication with OEM ECU via CAN bus

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