Engines and Vehicle Management System - Systems engineering

Introduction to engine management system

1. AT 17701 – Engine& Vehicle Management System Session 7 17-10-2021 1

2. Unit 2 SI Engine Management System MPFI System – Layout and Working Phases of SI Engine Control – Cold start and Warm up phases, idle speed control, acceleration and full load enrichment, deceleration and fuel cut-off Cylinder deactivation Fuel control maps Gasoline Direct Injection Catalytic emission control 17-10-2021 2

3. Recap of session 6 Gasoline engine fundamentals Effect of A/F ratio on engine emissions Emission Norms 17-10-2021 3

4. Gasoline Fuel Injection Systems 17-10-2021 4

5. Carburetor Throttle body injection Port injection Direct injection Evolution of fuel injection technology in Gasoline engine Lower emission & improved fuel economy

6. 17-10-2021 6 Gutbrod Superior 600 Goliath GP 700

7. Multipoint Fuel Injection (MPFI) System MPFI system was originally only developed for the airplane engines nowadays, it is widely used in light commercial vehicles. MPFI system is the most advanced gasoline injection system the automobile industry currently has. It is a perfect blend or combination of electronics, mechanical, computer and electrical engineering that make this system more advanced. The MPFI system aims at supplying proper ratio of gasoline and air to the engine to achieve improved fuel consumption and lower emissions. 17-10-2021 7

8. Multipoint Fuel Injection (MPFI) System Advantages The power generated by the engine is more than the carburetion system. Due to the accurate mixture of air-fuel supplied to each cylinder, the difference between power generated at each cylinder is negligible. Engine vibrations from MPFI equipped engines are very less, hence the life of MPFI system equipped engines is high. This system is very responsive in case of sudden acceleration or deceleration. Lower fuel consumption leads to better mileage. The volumetric efficiency of MPFI is high. Disadvantages The system is complex hence costly. It requires more space. 17-10-2021 8

9. Manifold injection F ormation of the air/fuel mixture begins outside the combustion chamber in the intake manifold. High standards of smooth running and emission behavior - leads to strict requirements with respect to the formation of the air/fuel mixture. Precise metering of the injected fuel mass – matched to the air mass inducted by the engine – perfectly timed injection and targeting of the spray are crucial. This system injects the fuel intermittently, and individually, for each cylinder directly onto its intake valves. 17-10-2021 9

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12. Cold starting When the ignition key is turned, the starter rotates and turns the engine over at starter speed. The signals from the speed and phase sensors (Fig. 2, Pos. 14 and 7) are collected. The Motronic ECU uses these signals to determine the piston positions of the individual cylinders. The injected fuel quantities are calculated in accordance with the program maps stored in the ECU and transmitted via the fuel injectors. The ignition is then activated. Engine speed is increased with the first combustion. 17-10-2021 12

13. 17-10-2021 13 Cold starting is characterized by different phases Starting phase Post-start phase Warming-up Catalytic-converter heating

14. Instants of injection In addition to the correct injection duration, a further parameter which is important for optimization of the fuel-consumption and exhaust-gas figures is the instant of injection referred to the crankshaft angle. The instant of injection for each individual cylinder - pre-intake and intake-synchronous injection. The instant of injection of all the cylinders Simultaneous fuel injection Group fuel injection Sequential fuel injection Cylinder-individual fuel injection 17-10-2021 14

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16. Engine functions and control diagram 17-10-2021 16

17. Major controller inputs from engine 17-10-2021 17

18. Major controller outputs to engine 17-10-2021 18

19. Typical variation of performance with a variation in air/fuel ratio 17-10-2021 19

20. Representative variation of performance with spark timing 17-10-2021 20

21. NOx emission as a function of air/fuel ratios at various EGR% 17-10-2021 21

22. Influence of EGR on brake-specific performance variables 17-10-2021 22

23. Conversion efficiency of a TWC versus air/fuel. 17-10-2021 23

24. ELECTRONIC FUEL CONTROL SYSTEM 17-10-2021 24

25. BOSCH D- Jectronic Fuel Injection System The Bosch-engineered D- Jetronic comprises a gasoline-injection system that is essentially controlled by intake-manifold pressure and engine speed. D- Jetronic (D stands for “ drucksensorge - steuert ” – German for pressure-sensor controlled) 17-10-2021 25

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28. Adaptation to operating conditions Adaptations under different operating conditions are required to ensure good engine performance: Full load : The fuel quantity is determined for maximum power. Acceleration enrichment : Additional injection pulses are applied during acceleration. Altitude compensation : It is possible by taking into account the pressure differential between intake manifold and free atmosphere to obtain good adaptation of fuel injection to different altitudes. Intake-air temperature : The temperature dependent density differences of the air can be taken into account by recording the outside temperature. 17-10-2021 28

29. BOSCH L- Jectronic Fuel Injection System L- Jetronic is an electronically controlled fuel-injection system which injects fuel intermittently into the intake manifolds. It does not require any form of drive. The main measured variables are the engine speed and the amount of air drawn in by the engine. These variables determine the basic injection period. 17-10-2021 29

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31. Adaptation to operating states Cold-start enrichment : As a function of engine temperature, an additional quantity of fuel is injected for a limited period during starting. Enrichment is achieved by extending the injection period or by injecting an additional quantity of fuel via the cold-start valve. The injection period of the cold-start valve is limited by a thermo-time switch depending on the engine temperature. Post-start and warm-up enrichment : Engine cold starting is followed by its warming-up phase. During this phase, the engine needs warm-up enrichment since some of the fuel condenses on the still cold cylinder walls. In addition, without supplementary fuel enrichment during the warm-up period, a major drop in engine speed would be noticed after the additional fuel from the cold-start valve has been cut off. When post-start enrichment has finished, the engine needs only a slight mixture enrichment, this being controlled by the engine temperature. 17-10-2021 31

32. Adaptation to operating states Acceleration enrichment: If the throttle valve is quickly opened (acceleration), the amount of air which enters the combustion chambers plus the amount of air which is needed to bring the manifold pressure up to the new level flows through the air-flow sensor. This causes the sensor plate to “ overswing ” past the wide- openthrottle point. This “ overswing ” results in more fuel being metered to the engine and ensures good transition response. Idle-speed control: The air-flow sensor contains an adjustable bypass via which a small quantity of air can bypass the sensor plate. The idle-mixture-adjusting screw permits a basic setting of the air/fuel ratio by varying the bypass cross-section. An auxiliary-air device, which is connected as a bypass to the throttle valve, directs auxiliary air to the engine, depending on the engine temperature, in order to achieve smooth idling when the engine is cold. 17-10-2021 32

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34. 17-10-2021 34 Engine Idle Speed Control

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37. 17-10-2021 37 Cylinder Deactivation

38. Cylinder Deactivation 17-10-2021 38

39. Cylinder Deactivation If you want to save fuel, one of the easiest ways is to not to use it. That’s the idea behind cylinder deactivation, used by some automakers to help improve fuel economy and reduce emissions. Deactivation is mostly used on V6 or V8 engines, where, in principle, it reduces the engine’s displacement when it functions: Bigger-engine power when all cylinders are activated, and smaller-engine fuel economy when some are shut off.  Essentially, deactivation is a larger engine that can act like a smaller one, while turbocharging is a smaller engine that can perform like a larger one. (Some automakers combine deactivation and turbocharging on their engines, as well.) 17-10-2021 39

40. Cylinder Deactivation Cylinder Deactivation, or CDA,  is a technique in multi-cylinder engines where a combination of cylinders are systematically disabled, effectively reducing the engine’s displacement, improving overall engine efficiency and fuel economy.  CDA is achieved by deactivating the intake and exhaust valves for the deactivated cylinder. This can be done on multiple cylinders of an engine providing variations of active cylinder displacement. For gasoline engines, this is done to improve pumping work and increase fuel economy.  Cylinder deactivation is not just for gasoline engines.  In diesel engines, cylinder deactivation is used for the purpose of exhaust heating. By deactiving cylinders at low loads, the remaining active cylinders work harder and produce more heat, which gets the aftertreatment system hotter quicker and reduces emissions. 17-10-2021 40

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43. 17-10-2021 43 Cylinder Deactivation

44. Cylinder Deactivation 17-10-2021 44

45. Cylinder Deactivation If you want to save fuel, one of the easiest ways is to not to use it. That’s the idea behind cylinder deactivation, used by some automakers to help improve fuel economy and reduce emissions. Deactivation is mostly used on V6 or V8 engines, where, in principle, it reduces the engine’s displacement when it functions: Bigger-engine power when all cylinders are activated, and smaller-engine fuel economy when some are shut off.  Essentially, deactivation is a larger engine that can act like a smaller one, while turbocharging is a smaller engine that can perform like a larger one. (Some automakers combine deactivation and turbocharging on their engines, as well.) 17-10-2021 45

46. Cylinder Deactivation Cylinder Deactivation, or CDA,  is a technique in multi-cylinder engines where a combination of cylinders are systematically disabled, effectively reducing the engine’s displacement, improving overall engine efficiency and fuel economy.  CDA is achieved by deactivating the intake and exhaust valves for the deactivated cylinder. This can be done on multiple cylinders of an engine providing variations of active cylinder displacement. For gasoline engines, this is done to improve pumping work and increase fuel economy.  Cylinder deactivation is not just for gasoline engines.  In diesel engines, cylinder deactivation is used for the purpose of exhaust heating. By deactiving cylinders at low loads, the remaining active cylinders work harder and produce more heat, which gets the aftertreatment system hotter quicker and reduces emissions. 17-10-2021 46

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49. Cylinder deactivation prerequisite Engine speed – 1250 – 4000 rpm Torque = 100 N.m Oil temperature = min. 10 deg. C Coolant temperature = min. 30 deg. C Lambda control is active 17-10-2021 49

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51. 17-10-2021 51 Stages of Active cylinder deactivation Engine switches from 4 cylinder to 2 cylinder mode

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53. 17-10-2021 53 Stages of Active cylinder reactivation Engine switches from 2 cylinder to 4 cylinder mode during acceleration

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56. Gasoline Direct Injection 17-10-2021 56

57. Major objectives of GDI engines Ultra–low fuel consumption that betters that of even diesel engines. Superior power compared to MPFI engines. 17-10-2021 57

58. Gasoline Direct Injection Gasoline direct-injection engines generate the air/fuel mixture in the combustion chamber. During the induction stroke, only the combustion air flows through the open intake valve. The fuel is injected directly into the combustion chamber by special fuel injectors. 17-10-2021 58

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61. Combustion in GDI engines In the case of gasoline direct injection, the combustion process is defined as the way in which mixture formation and energy conversion take place in the combustion chamber. The mechanisms are determined by the geometries of the combustion chamber and the intake manifold, and the injection point and the moment of ignition. Depending on the combustion process concerned, flows of air are generated in the combustion chamber. The relation to those combustion processes which work with charge stratification (stratified concepts). In order to obtain the required charge stratification, the injector fuel injects the fuel into the air flow in such a manner that it evaporates in a defined area. The air flow then transports the mixture cloud in the direction of the spark plug so that it arrives there at the moment of ignition 17-10-2021 61

62. Homogeneous Combustion Mode In the case of the homogeneous combustion process, usually a generally stoichiometric mixture is formed in the combustion chamber in the engine map i.e. an air ratio of λ = 1 always exists. In this way, the expensive exhaust-gas treatment of NO X emissions which is required with lean mixtures is avoided. Homogeneous concepts are therefore set out to be emission-reducing concepts. 17-10-2021 62

63. Stratified Charge Combustion Mode In the case of the stratified-charge combustion process, the fuel is injected in a specific map range (small load, low engine speed) first during the compression stroke into the combustion chamber, and transported as a stratified-charge cloud to the spark plug. 17-10-2021 63

64. Stratified Charge Combustion Mode The cloud here is ideally surrounded by pure fresh air. In this way, an ignitable mixture is only present in the local cloud. An air ratio of greater than 1 exists generally in the combustion chamber. This enables the engine to be operated unthrottled in greater ranges, which results in increased efficiency on account of the reduced pumping losses. Stratified-charge combustion processes are therefore run predominantly as a fuel-consumption concept. 17-10-2021 64

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67. 17-10-2021 67 End of session 7