Engine Management Systems and Calibration Shaping the Future Engine Management Systems and Calibration

Engine Management Systems The basic role of an Engine Management System is to provide precise control of engine operation by managing fuel supply, ignition, and the quantity of air inducted into the engine At the heart of every Engine Management System is an electronic control module (ECM), which is an on-board computer incorporating a digital microprocessor. The ECM is linked to the engine by means of sensors installed on the engine (to read data about the operating conditions of the engine), and actuators such as ignition coils, stepper motors, relays, etc as the means for effecting control on engine operation. The modern EMS also has to provide a comprehensive level of self-diagnosis in the case of faulty components or engine operation. This is referred to as On-Board Diagnostics (OBD).

Engine Management Systems Engine Control Module (ECM) Sensors Actuators

Engine Management Systems Early EMS Fuel Tank ECM Fuel Pump Distributor Based Spark Ignition Throttle Position Sensor Port Fuel Injector Cold Start Injector Gate – Air Mass Flow Meter Idle Speed By-Pass

Engine Management Systems Bosch L-Jetronic

Engine Management Systems

Engine Management Systems Wide Band – Linear Lambda Sensor Bosch Motronic MED EMS (Direct Petrol Injection)

Typical Functions of an EMS Spark Advance Control (with or without Waste Spark) Knock Control through Adaptive Spark Advance Idle Speed Control Independent Cylinder Fuel Injection (inc Multi Strike) Exhaust Gas Recirculation Control Adaptation for Alternative Fuels Charcoal Canister Purge Control Cam Phasing and Valve Lift Variable Geometry Turbocharging and Intake Systems Full Diagnostics (compliance with OBD legislation) Cylinder Disablement for torque control Engine Temperature Management

Main Components of an EMS Electronic Control Module (ECM) Crankshaft Speed Sensor Camshaft Position Sensor Fuel Pump Fuel Injectors Fuel Pressure Regulator Air Mass Flow Meter Manifold Absolute Pressure Sensor Throttle Position Sensor Throttle Actuator Exhaust Gas Recirculation Valve Idle Speed Air By-Pass Valve Exhaust Gas Oxygen Sensor Ignition Coil Spark Plug Sensors and Actuators

Sensors - Speed & Position Variable Reluctance Crankshaft Speed Sensor Hall Effect Camshaft Position Sensor A voltage is generated transversely (between points E and F) to the direction of current flow (A to B) if a magnetic field is applied perpendicularly to the conductor. (usually a semiconductor)

Sensors – Mass Air Flow Air Mass Flow Meter

Sensors – Oxygen Sensor Oxygen or Lambda Sensor

Engine Control Module (ECM) Delphi MT80 Control Module

EMS Control Overview Fundamentally the Engine Management System (EMS) attempts to control the highly complex thermodynamic functions that define the continuously varying engine operating conditions, by providing the right quantities of air, fuel, timing of ignition, exhaust gas recirculation etc. A theoretical approach to this problem would be to incorporate a complex set of mathematical models or algorithms that define every possible condition. The EMS would then only have to run these models in real time to correctly supply the desired fuel, air, egr and ignition advance.

EMS Control Overview Algorithms used in the EMS are models that describe the operation of a particular function for given values of input data but also use some previously determined empirical data (maps) An EMS will have a wide range of relatively simple models (also known as strategies) for specific control functions

Instructions to Actuators EMS Control Overview Data from Sensors Instructions to Actuators Structured 2-D and 3-D Maps or “Look Up Tables” (Maps) and algorithms (“Strategy”)

EMS Control Strategies Spark Advance Control (with or without Waste Spark) Knock Control through Adaptive Spark Advance Idle Speed Control Independent Cylinder Fuel Injection (inc Multi Strike) Exhaust Gas Recirculation Control Adaptation for Alternative Fuels Charcoal Canister Purge Control Cam Phasing and Valve Lift Variable Geometry Turbocharging and Intake Systems Full Diagnostics (compliance with OBD legislation) Cylinder Disablement for torque control Engine Temperature Management

EMS Strategy Example Idle Speed Control Idle speed variation is caused by; Changes in auxiliary power take off requirements, for example air compressors and alternators. Combustion performance variability (eg COV of IMEP) Driver input – “blipping the throttle” The task of the idle speed control system is to primarily manage the step torque demands of the auxiliary systems through air flow control and ensure that the idle speed is kept as low as possible

EMS Strategy Example Idle Speed Control Inputs Outputs Engine Speed Engine Load (Man Abs Press) Dynamic Control Loops Energy conversion Intake manifold Torque balance Outputs Air mass flow modulator Plant Model (algorithms & maps)

EMS Strategy Example Idle Speed Control Air Manifold Pressure Engine Speed Intake air flow rate Man Press Engine Torque Engine Friction Load

EMS Strategy Example Idle Speed Control Manifold Air Mass Outflow Estimation (Map) Engine Speed Manifold Pressure Integrator Manifold Air Mass Inflow dpm /dt = (1/)  dmin/dt – dm*out/dt 

EMS Strategy Example Idle Speed Control Engine Speed Engine Speed Integrator Man Press Combustion Torque Pulse per Cylinder (Map) Torque Delay due to cylinder firing order (dead time & lag) 2J (dn/dt) = Tcomb - Tload

Air Mass Flow Modulator EMS Strategy Example Idle Speed Control Air Mass Flow Modulator Proportional & Integral Controllers

“The process of determining the calibre of a gun” Engine Calibration Term coined in late 1980s The precise measurement and optimisation of the characteristics of an engine and drive train in all possible vehicle model variants A Calibration Engineer instigates the measurement of the engine characteristics and subsequently decides which are the optimum The Engineer includes the optimum values within the engine EMS Calibration “The process of determining the calibre of a gun” Brian Hall

Typical Calibration Programme Initial calibrations based on previous experience Testing of prototype engines on an engine dynamometer Calibration transferred to vehicle for refinement Successive approximations Homologation Final Calibration Validation Sold to production +90 days support 2 to 3 Years Brian Hall

“Tools of the Trade” Engine Test Cell Vehicle Chassis Dynamometer Linear AFR sensor Measurement & Calibration (Interface) System Automated Calibration System Cold and Hot chambers (and/or equivalent ambients) Emissions Lab Test Track Analysis tools Excel Matlab Simulink Model Based Calibration toolbox Brian Hall

Measurement & Calibration System e.g. AVL CAMEO e.g. ATI Vision Brian Hall

MCS Calibration Tool – ATI Vision Brian Hall

MCS Calibration Tool – ATI Vision Engine Speed Lambda Throttle Position Brian Hall

MCS Calibration Tool – ATI Vision Brian Hall

Automated Calibration – AVL Cameo Optimises Engine Testing using Design of Experiments Models to gather data for EMS Maps Brian Hall

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