英文资料及中文翻译

天津职业技术师范大学2014届本科生毕业论文

Engine Management System

Moronic combines all the electronic systems for engine control in a signal control unit (ECU) which, in turn, governs the actuating systems used to control the spark-ignition engine. Engine-mounted monitoring devices (sensors) gather the required operating data and relay the information to input circuits for. ? ignition (on/off) ? camshaft position ? vehicle speed ? gear selection ? transmission control ? air conditioner, etc. Monitored analog data include: ? battery voltage ? engine temperature ? intake-air temperature ? air quantity ? throttle-valve angle ? lambda oxygen sensor ? Knock sensor, etc. as well as ? engine speed

Input circuits located within the ECU convert these data for subsequent operations in the microprocessor. The microprocessor, in turn, uses these data to determine the engine’s momentary operating conditions; this information serves as the basis for the ECU’s to the final –control elements used to control the engine. This system com bines fuel injection, highest-quality mixture preparation and the correct ignition timing to provide mutual support over the entire range of operating conditions encountered in the spark-ignition engine. Moronic versions

The descriptions and illustrations on the following pages refer to a typical Moronic configuration. Other Moronic systems are available to meet the special demands arising from specific national regulations as well as the requirements of the individual automobile manufacturers.

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天津职业技术师范大学2014届本科生毕业论文

Basic functions

Control of the ignition and fuel-injection processes is (independent of version) at the core of the moronic system. Auxiliary functions

Additional open and closed-loop control functions – required in response to legislation aimed at reductions in exhaust emissions and fuel consumption – supplement the basic Moronic functions while making it possible to monitor all components exercising an influence on the com- opponents of the exhaust gases. These include: ? Idle-speed control ? Lambda oxygen control

? Control of the evaporative emissions control system, ? Knock control

? Exhaust-gas recirculation (EGR) for reducing NOx emission, and ? Control of the secondary air injection to reduce HC emissions.

The system can also be expanded to meet special demands from automobile manufacturers by including the following;

? Open-loop turbocharger control as well as control of variable-tract intake

manifolds for increased engine power output, and

? Knock control along with engine and vehicle-aped governing functions, to protect

engine and vehicle. Vehicle management

Moronic supports the control units in other vehicle systems . It can, for instance, operate together with the automatic transmission’s control unit to provide reductions in torque during shifting, thereby lessening transmission wear. Moronic can also work together with the ABS control unit to provide traction control (ASR) for enhanced vehicle safety.

The schematic system illustration below shows a maximal-configuration Moronic system. This type of system can be employed to satisfy The stringent emissions limits, and

The requirement for an integral, onboard diagnosis (OBD) system for California vehicle from 1993 onward.

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天津职业技术师范大学2014届本科生毕业论文

Processing operating data Processing load signals Monitored variables

The ECU uses the signals for load and engine speed to calculate a load signal corresponding to the air mass inducted into the engine during each stroke. This load signal seers as the basis for calculation of injection duration and for addressing the programmed response curves for ignition advance angle. Monitoring air mass

Hot-wire or hot-film air –mass meters measure the air mass directly, producing a signal that is suitable for use as a parameter in load-signal calculations. When an air-flow meter is used, density correction is also required before air mass and load determined.in special cases monitoring errors due to heavy pulsation in the intake manifold also receive compensation in the form of a pulsation correction. Monitoring pressure

Pressure-monitoring systems (using a pressure sensor to determine load )

Differ form air-mass monitoring systems in that1 no direct formulas are available for defining the relationship between intake pressure and the air-mass intake. The ECU therefore calculates the load signal with the aid of corrections stored in a program map. Subsequent compensation is provided for changes in temperature and residual gas relative to the initial state. Measuring throttle-valve angle

When a throttle-valve sensor is used, the ECU determines the load signal with reference to engine speed and throttle-valve angle. Compensation for variations in air density are based on 1 readings 2 for temperature and ambient pressure. Calculating injection timing Base injection timing

The base injection timing is calculated directly from the load signal and from the injector constants, and defined the relationship between the duration of the activation signal and the flow quantity at the injector. This constant thus varies according to injector design. When the injection duration is multiplied by the injector constant the result will be a fuel mass corresponding to a particular air mass for each stroke. The base setting is selected for an excess-air factor of λ=1.

The remains valid for as long as the pressure differential between fuel and intake manifold stays constant. When it varies, aλ correction map compensates for this

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天津职业技术师范大学2014届本科生毕业论文

influence on injection times.

Meanwhile, a battery-voltage corrector compensates for the effects that fluctuations in battery voltage have on the injectors’ opening and closing times. Effective injection time

The effective injection results when the correction factors are included in the calculations. The correction factors are determined in corresponding special functions and provide adjustment data for varying engine operating ranges and conditions. The correction factors are used both individually and in combinations according to applicable parameters.

The process for calculation the injection time is illustrated in Figure.

Once cylinder filling drops below a certain level, the mixture will cease to ignite. Restricting the injection time thus prevents the formation of unburned hydrocarbons in the exhaust gas.

For starting, the injection time is calculated separately using criteria independent of the calculated load signal. Injection mode

In addition to the injection time, the injection mode is yet another important parameter for fuel economy and exhaust emissions. The range of options depends upon the type of injection system: ? Simultaneous injection, ? Group injection, or ? Sequential injection. Simultaneous injection

With simultaneous injection, the injection process is triggered twice per cycle at a specific point in time at all injectors, that is, once for each camshaft revolution, or once for every two crankshaft revolutions. The injection mode is static.

Group injection group infection combines the injectors in two groups, with each group being triggered once per cycle. The time interval between the two triggering points is equal to one crankshaft rotation period. This arrangement makes it possible to use the engine operating point as the essential criterion in selecting the injection mode while also prevention undesirable spray through the open intake waves throughout a wide range in the program map. Sequential injection

This type of injection provides the highest degree of design of design latitude. Here,

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