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Published byHarry Evans Modified over 9 years ago
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8.1.2014
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4 STROKE ENGINE OPERATION Intake Stroke Compression Stroke Combustion Exhaust Stroke Different Engine states require different air/fuel concentration, different ignition advance
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MOTIVATION Most modern car engines are 4 stroke engines. To achieve maximum efficiency. the engine must be supplied with precise fuel amounts (Air-Fuel Ratio). fuel must be burn at the ideal time when the pistons move up and down (Ignition Advance). SoC are very cheap For these – we need fast input and output access, in the ~10us range.
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PROJECT GOALS Design a real time system that reads engine sensors and : Determine the ideal spark time Determine the ideal air-fuel mixture enable easy updating of the ECU via the built in SD-CARD Affordable Designed for a 4cylinder engine
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NAÏVE ARCHITECTURE ECU Sampling rate of 233hz !
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SOLUTION : FINAL ARCHITECTURE 2 nd Arduino UART DigitalAnaloginputs
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SOLUTION : FINAL ARCHITECTURE ECU Outputs :Fuel, Ignition pulses Inputs :Engine sensors (MAP,CLT,IAT,CRANK,TPS,O2)
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BLOCK DIAGRAM Load Tables from SD-card StreamSend RX Calc Ign Adv, Inj PW StreamSend TX Read Sensors StreamSend TX StreamSend RX Calc Inj, Ign times Crank Sensor Drive Outputs Arduino Galileo
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Calc desired angle for event REAL TIME PROGRAMMING Calc time untill event Schedule event : time to start, duration Wait untill : current_time=interrupt_time End funcStart func interrupt time=current_time+ duration interrupt time=current_time+ time_to_start
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TESTING ENVIRONMENT ECU Galileo+Arduino Nano D2: Crank (timerInterrupt driven) LPF PWM: MAP TPS COOLANT IAT Analog voltages Each engine scenario is a different test bench code Engine simulator
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TEST SCENARIOS Accelerate – Increasing RPM. more sparks and increased fuel amount Decelerate – Decreasing RPM. less sparks and decreasing fuel amount Warming Engine – Increasing COOLANT. decreasing fuel amount. Slope – Increasing TPS. increasing fuel amount High Load – Increasing MAP. Increasing fuel amount
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ACCELERATION SIMULATION RESULTS
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WARMING ENGINE SIMULATION RESULTS
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STEEP SLOPE SIMULATION RESULTS
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DECELERATE SIMULATION RESULTS
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HIGH LOAD SIMULATION RESULTS
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NEXT STEPS? engine1engine2 serial0 serial1
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NEXT STEPS? engine1engineN I2c BUS engine2 …
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BACKUP
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