Session 1, 2, &3 of the course of ICE.pptx

Calculations and describtions

1. Fuel systems – SI engines

2. Outline Objective of fuel systems Classification of fuel systems Evolution – technology, regulations Carburetor-based fuel systems Electronic Fuel Injection (EFI) systems Engine control – fundamentals Air/fuel mixture and combustion control subsystems Injection, idle speed and throttle position, fuel pump/pressure, ignition, s uperch a rging Exhaust subsystem exhaust, EGR, oxygen sensors heating Other subsystems controlled by the engine ECU Radiator fan, Variable valves timing control, A/C compressor control, OBD/Check engine lamp Sensors Actuators

3. Sis t emas Aut o mó v eis Main objective is to deliver fuel into the cylinders at proper timings (optimizing power) in correct amounts (for optimal A/F ratio, function of load, RPM, engine temperature,…) in the right form (fuel atomization, for full combustion and lower emissions)

4. Classification of fuel systems (CI and SI) Op e r a ti n g principle ICE type single or multiple injectors di r e ct/indi r e ct injection technology Mechanical SI (single point) indirect Carburetor Diesel (multi-point) direct or indirect Injection Pump (in-line or rotary), few hundred bars Electronic SI SPI indirect in the throttle body, few bars MPI indirect Fuel rail, few bars direct Fuel rail, tens of bars Diesel (multi-point) direct Fuel-rail or pump/unit- injection, hundreds to thousands of bars

5. Sistemas Automóveis Classification of fuel systems Fuel system types “Mechanical” (increasingly electronically assisted) SI – mostly used until the dawn of “electronics” (< 1960) materialized by the “ Carburetor ” CI – still in use, but gradually changing to “common rail” materialized by the “ Injection Pump ” (in the figure)

6. Classification of fuel systems Fuel system types “Electronic” (ECU-based) Single-Point Injection (SPI) – Figure a) Aka “throttle-body injection” mostly used in low-cost small-sized SI engines Multi-Point Injection (MPI) Indirect (external) – Figure b) SI: injection is done upstream (the intake valves) Diesel: injection is done in a pre-chamber Direct (internal) – Figure c) pressure accumulator/common-rail systems (SI + most Diesel) pump/unit-injector systems (few Diesel)

7. Evolution – fuel injection technology

8. Evolution – European emission standards

9. Evolution – emission reduction vs. technologies

10. Carburetor-based fuel systems Basic carburetor operation air is drawn into the engine by the pumping action of the pistons (vacuum) the air accelerates as it passes through the venturi , causing a slight drop in pressure. this pressure drop pulls fuel from the float bowl (through a nozzle) into the throttle body it then mixes with air in a fine mist, which is distributed to the cylinders through the intake manifolds the choke valve enables the driver to control (enrich) the mixture, at cold start

11. Carburetor-based fuel systems Main problems Controlling fuel quantity accurately dependent on vacuum (not on fuel injection pressure/duration) insensitive to air temperature, pressure, humidity, engine temperature, RPM, throttle position,… Controlling fuel quantity in real-time delayed/reactive response Even delivery of air/fuel mixture across all cylinders (intake manifolds) Hard cold-start flooded carburetor… Fuel consumption 12-15 litres per 100 km was common Pollution high hydrocarbons in exhaust gases

12. Electronic fuel injection (EFI) systems EFI emerged due to stringent exhaust emission regulations Increasing fossil fuel cost evolution of analog/digital electronics Basics fuel pump compresses fuel fuel accumulator (rail) stores fuel electrically controlled injectors spray the fuel into intake manifold or combustion chamber ECU controls injection timing/duration for optimal engine control reduced emissions reduced fuel consumption maximized performance

13. EFI systems: Single-Point Injection (example) Mono-Jetronic (1988–1995) one lambda sensor mechanical fuel pressure regulator first generation ignition system first generation on- board diagnosis ronic_blo ck_diagram.gif

14. de 2016 | 14 EFI systems: Multi-Point Injection (example 1) D-Jetronic (1967–1976) "Speed-Density" fuel injection, i.e. there is no Air Flow Meter (AFM) air-mass flow is measured indirectly, by measuring intake air pressure (3), temperature ( not numbered ), RPM (not in figure) and knowing cylinder volume

15. EFI systems: Multi-Point Injection (example 2) L-Jetronic (1974–1989) L stands for Luft (air) flow meter (AFM) first generation ignition flap type AFM (11) hp

16. EFI systems: Multi-Point Injection (example 3) Motronic (1987-1998) integrates injection and ignition (ECU controls both) fuel pressure accumulator (fuel rail) more sensors proliferate second generation ignition system intake air mass flow is “directly” measured by air- flow meter (12, flap type)

17. EFI systems: Multi-Point Injection (example 4) Gasoline Direct Injection

18. EFI systems: Multi-Point Injection (example 5) Toyota Computer- Controlled System (TCCS) 1994 3VZ-E engine

19. Aut o mó v eis Fuel supply system example (E38/E39 – base for BMW 7 Series 1995-2001)

20. Fuel supply system example (E38/E39 – base for BMW 7 Series 1995-2001) Emphasis on the fuel tank

21. Engine control - fundamentals Computer-controlled closed loop fault-tolerant real-time networked Controls fuel injection ignition ISC, EGR, … Composed of inputs (sensors) outputs (actuators) controller (ECU) network (e.g. CAN)

22. Engine control – DGI computer architecture (example 1) OEM

23. Engine control – DGI computer architecture (example 2) OEM

24. Outline Fuel systems classification SI fuel systems evolution Carburetor-based fuel systems Electronic Fuel Injection (EFI) systems Engine control – fundamentals Air/fuel mixture and combustion control subsystems Injection

25. Fuel injection – algorithm (1) Base fuel volume engine RPM engine load Corrections exhaust oxygen water temp. accelerator pedal air temperature air pressure knock voltage

26. Fuel injection – algorithm (2) Computation of fuel injection duration (volume/mass) Baseline (target) fuel volume is computed according to engine load engine load = air mass flow divided by engine speed > air mass flow  > injection duration ECU selects closed- or open-loop mode based on throttle opening, engine speed, vehicle speed, and fuel trim and air flow maps closed-loop: normal engine operation (A/F  14,7) open-loop: cold engine/strong accel/desaccelation (A/F < 14,7) Corrections to the target fuel volume based on several parameters (see flowchart) and an injector pulse width calculated all these computations must be made in a few milliseconds for an optimal (real-time) control of the engine

27. 016 | 27 Fuel injection – algorithm (3) Example “ fuel map ” (for computing the base fuel volume) A/F ratio is optimized for best trade-off of power, fuel economy, low emissions and knock prevention lower load & RPM  leaner mixture (A/F > 14,7) higher load & RPM  richer mixture (A/F < 14,7) ECU interpolates between values

28. Fuel injection – algorithm (4) Correction according to coolant temperature fuel vaporization gets poorer for colder engine (specially < 80 ºC) injection duration is increased (A/F mix enrichened) for lower temperatures

29. Fuel injection – algorithm (5) Correction according to intake air temperature a change in air temperature changes the air density air density varies inversely proportionally with air temperature > temperature  < density the colder the air, the denser it becomes (more air mass for the same air volume) more fuel must be injected to keep the same air/fuel ratio

30. Fuel injection – algorithm (6) Correction according to atmos ph eric pressure air density varies proportionally with air pressure > pressure  > density air pressure varies inversely proportionally with altitude < altitude  > pressure lower altitude  higher density  higher pressure more fuel must be injected to keep the same air/fuel ratio

31. Fuel injection – algorithm (7) Correction according to accelerator pedal fuel is denser than air thus cannot move into the cylinder as quickly during engine acceleration so, a momentary lean condition may occur to compensate for this, the injection duration is increased extra injection pulses also may be delivered Injection duration is reduced during deceleration to improve fuel economy and emissions.

32. Fuel injection – algorithm (8) Correction according to charging system voltage current through the injector solenoid  needle valve is pulled up latency (dead time) between when the current starts and the valve is fully open injector valve speed depends on applied voltage > voltage  > current  < injector opening time injector must be activated earlier for lower voltages and later for higher voltages the actual opening period of the injector remains the same

33. Fuel injection – algorithm (9) Correction according to oxygen in exhaust gases ECU uses U O2 in a feedback (closed) loop to restrict A/F ratio to a narrow range where catalyst is most efficient (A/F = 14.7  1%) U O2 > 0,5 V  rich mix  reduce fuel injection U O2 < 0,45 V  lean mix  increase fuel injection

34. Outline Fuel systems classification SI fuel systems evolution Carburetor-based fuel systems Electronic Fuel Injection (EFI) systems Engine control – fundamentals Air/fuel mixture and combustion control subsystems Injection, idle speed and throttle position

35. Idle speed and throttle control Idle (or idling) state An ICE is considered to be “idle” if the two following conditions apply The throttle pedal/grip is not depressed The engine is uncoupled to the drivetrain (either in neutral or with the clutch activated) Idle speed is the rotational speed of the crankshaft at idle state usually measured in revolutions (rotations) per minute (RPM) Idle Speed Control (ISC) ( Idle Air Control (IAC)) Idle speed must be optimized so that The engine runs smoothly (without vibrations) The engine generates enough power to operate ancillary devices alternator, A/C, water/oil pumps, power steering Fuel consumption is minimized (lowest RPM)

36. Idle speed and throttle control Typical idle RPM: passenger-car = 600 – 1,000 buses/trucks = 500 – 600 motorcycles = 1000-1500 Idle Speed Control can be purely mechanical as in carburetor-based fuel systems ECU-based , through the control of either bypass ISC valve (in the intake manifold) inputting air upstream and outputting air downstream of the throttle valve throttle valve Electronic Throttle Control (ETC), Throttle Actuator Control (TAC) , or Throttle-By-Wire

37. Idle speed and throttle control Throttle (valve) valve that controls the flow of intake air by opening/closing of a rotating plaque (aka butterfly ) integrated in the throttle body

38. Idle speed and throttle control Bypass ISC valve (aka idle air control (IAC) valve) controls the flow of intake air through a bypass to the throttle inputting air upstream the throttle outputting air downstream the throttle operating principles DC motor + worm drive step (servo) motor solenoid valve

39. Idle speed and throttle control Throttle (valve) its actuation can be purely mechanically-controlled (driven by a cable or rod) ECU-controlled ( throttle-by-wire )

40. Idle speed and throttle control Purely mechanically-controlled throttle up to the nineties, throttle opening/closing was directly (mechanically ) driven by a cable connected to the driver’s accelerator pedal/grip driver pressing the accelerator = throttle opened driver not pressing the accelerator = throttle closed  “idle” state ISC is purely mechanical, via the following mechanisms manual adjustment of air bypass (screw) manual adjustment of throttle position (cable; stop screw) automatic adjustment of air bypass according to coolant temperature (thermal valve)

41. Idle speed and throttle control ECU-controlled throttle throttle-by-wire has been emerging since the nineties BMW was the first vehicle manufacturer to offer electronic throttle control in the 7-Series (1988) accelerator cable gradually replaced by ECU + throttle actuator either the driver is pressing the accelerator or not, the throttle is ALWAYS controlled by the engine’s ECU driver not pressing the accelerator = “idle” state

42. Outline Fuel systems classification SI fuel systems evolution Carburetor-based fuel systems Electronic Fuel Injection (EFI) systems Engine control – fundamentals Air/fuel mixture and combustion control subsystems Injection, idle speed and throttle position, fuel pump/pressure

43. Fuel pump/pressure control Efficient fuel injection requires enough fuel flow (g/s) adequate fuel pressure (according to engine state) Main components fuel pump mechanically-driven by the crankshaft, through gears, chains or a toothed belt (often the timing belt) electrically-driven controlled by the ignition switch or by the engine ECU pressure regulator mechanical (diaphragm-controlled, not used nowadays) electrical (controlled by the engine ECU) fuel rail (if applicable) aka fuel accumulator or fuel distributor

44. Fuel pump/pressure control Fuel systems can have 1 or 2 fuel pumps 1 pump fuel systems low pressure (few bars) used in ordinary SI engines (figure) high pressure (hundreds of bars) used in CI engines in-line distributor-type common-rail

45. Fuel pump/pressure control Fuel systems can have 1 or 2 fuel pumps 2 pumps primary pump (low pressure) few bars secondary pump (high pressure) hundreds of bars used in CI unit-injector CI common rail SI direct injection (fig.)

46. Fuel pump/pressure control Pressure regulators are crucial for optimizing fuel injection, and can be purely mechanically-controlled diaphragm-controlled, not used nowadays guarantees a “constant” pressure differential between the fuel pressure in the accumulator and the air depression in the intake manifold electrically-controlled controlled by the engine ECU enables an optimized control of the fuel pressure in the fuel accumulator, according to engine/load conditions

47. Fuel pump/pressure control Mechanically-controlled fuel pressure regulator guarantees “constant” pressure differential between fuel pressure (in the “rail”) and intake air depression (intake manifold) operation throttle opens (left figure) intake air pressure increases return valve closes no fuel return to tank fuel pressure increases in “rail” throttle closes (right figure) intake air pressure decreases (vacuum) return valve opens fuel returns to tank fuel pressure decreases in “rail” 1 bar = 14,7 PSI (average air pressure at sea level

48. Fuel pump/pressure control Mechanically-controlled fuel pressure regulator

49. Fuel pump/pressure control ECU-controlled fuel pressure regulator (CI engine) Pressure Control Valve (PCV)

50. Fuel pump/pressure control ECU-controlled fuel pressure regulator (SI GDI engine) PCV is integrated with high-pressure fuel pump

51. Outline Fuel systems classification SI fuel systems evolution Carburetor-based fuel systems Electronic Fuel Injection (EFI) systems Engine control – fundamentals Air/fuel mixture and combustion control subsystems Injection, idle speed and throttle position, fuel pump/pressure, ignition, supercharging (forced air induction)

52. Supercharging Supercharging = forced air induction compress intake air  increase air mass (flow) power output is increased for a given displacement and engine speed Types mechanically-driven – supercharger directly driven by crankshaft (belt) exhaust-gas-driven – turbocharger driven by exhaust gases (turbine) hybrid (mechanically-driven) – twin-charger supercharger + turbocharger hybrid (electrically-driven) – electric supercharger electric motor/generator supporting the turbo/supercharger

53. Supercharging – supercharger Driven by the crankshaft through belt + pulley no turbo lag but requires some engine power

54. Supercharging – turbocharger waste gate  allows exhaust air to bypass the turbine (modulated by boost controller) pop-off valve  emergency pressure release (prevents excessive air pressure into combustion chamber) blow-off valve  prevents back-pressure in the compressor when throttle valve is abruptly shut

55. Supercharging – twin-charger < RPM  supercharger > RPM  turbocharger

56. Supercharging – electric turbocharger Series-hybrid turbocharger turbine-motor/generator-compressor < RPM Battery  motor  compressor > RPM turbine  generator  battery replacing the alternator?

57. 11 de outubro de 2016 | 58 Supercharging – electric supercharger Drive is fully electrical Particularly good for low RPM when engine power is low Tens of kW  hundreds of A  powerful alternator

58. Supercharging – hybrid supercharging • < RPM  supercharger • > RPM  turbocharger 11 de outubro de 2016 | 59

59. Outline Objective of fuel systems Classification of fuel systems Evolution – technology, regulations Carburetor-based fuel systems Electronic Fuel Injection (EFI) systems Engine control – fundamentals Air/fuel mixture and combustion control subsystems Injection, idle speed and throttle position, fuel pump/pressure, ignition, supercharging Exhaust subsystem exhaust, EGR, oxygen sensors heating

60. Exhaust system Objectives convey exhaust gases out of the engine reduce exhaust heat, noise and pollutant emissions, affecting engine power as little as possible Main components exhaust manifold  to draw exhaust gases out of the cylinders turbocharger (if applicable)  to increase engine power catalytic converter  to reduce pollutant emissions muffler(s)/silencer(s)  to reduce noise exhaust pipe(s)  to link the above components in order to convey and expel gases at a convenient point in the vehicle

61. Exhaust system Exhaust system outlook – SI engine

62. Exhaust gas recirculation (EGR) recirculates part of the exhaust gases into the intake 5-15% in SI engines up to 50% in CI engines EGR aim is to meet emissions standards most ICE (SI and CI) must have EGR some modern ICE do not need EGR e.g. use selective catalytic reduction (SCR) to reduce NOx

63. Exhaust gas recirculation (EGR) EGR leads to < oxygen admitted < peak in-cylinder temperatures < NOx emissions  < engine power  > particulate emissions (CI)  NOx reduction efficiency < for > oxygen % a given NOx reduction requires < EGR at high loads > EGR at low loads

64. Exhaust gas recirculation (EGR) EGR system can be low or high-pressure and includes ECU-controlled EGR valve EGR cooler (specially for SI engines)

65. Outline Objective of fuel systems Classification of fuel systems Evolution – technology, regulations Carburetor-based fuel systems Electronic Fuel Injection (EFI) systems Engine control – fundamentals Air/fuel mixture and combustion control subsystems Injection, idle speed and throttle position, fuel pump/pressure, ignition, supercharging Exhaust subsystem exhaust, EGR, oxygen sensors heating Other subsystems controlled by the engine ECU Radiator fan, Variable valves timing control, A/C compressor control, OBD/Check engine lamp Sensors Actuators

66. Engine control - sensors (sensors will be addressed in a separated module) IG/STA switch, neutral switch, A/C switch MAP, TPS Air Flow Meter Knock, RPM, Crankshaft/cam shaft position Fuel pressure/temperature Oxygen sensors (pre/post catalyzer) Alternator output voltage

67. Engine control - actuators (actuators will be addressed in a separated module) Fuel pump Radiator fan igniters Injectors Throttle control EGR control Fuel pressure regulator OBD/Check engine lamp Oxygen sensors heating Variable valves timing control A/C compressor control