ESC-爆震控制课件

1、Electronic Spark Control (ESC)Courtesy of Shawn HanFactors Affecting Knockcylinder and head designbase engine designAgingwear, carbon build-upcarbon build-uphot spots start auto-ignitioncompression ratiohigher CR increases knockingTemperaturehigher temperature increases knockingHumiditylower humidit

2、y increases knockingOctanehigher octane decreases knockingAlcoholhigher alcohol decreases knockingSupercharging (turbo)increases knockingAir-fuel ratio (altitude)leaner A/F increases knockingEGRmay cause A/F imbalance between cylindersSpark plug heat rangehotter increases knockingEngine loadhigher l

3、oad increases knockingRPMlower RPM less engine noise easier to hear knockingTIP INAF ratio goes lean. Trade off with emissions and driveabilityEquipment4-channel oscilloscope with FFTchecking windows, center frequencyBNC cable, terminating resistors (100k)listening devicedetermine correct detection

4、and no false detection/retardelectrical toolkitco-axial (shielded) cable, soldering iron, wire, terminals,Flashlight (torch)check pin assignments and connectionsInverterscope, listening device, computer, telephoneengine and chassis dynossteady state work in a stable environmentlow and high octane fu

5、elscheck windows and authority (maximum spark retard)low-quality low-octane fuel (pump says 90# but actually lower)Knock Analysis Instrument (KAI)hand-built computer and data collection device for sensor location study (10 were built in Kokomo)Spare sensors, connectors, terminalsSuction cupsto put D

6、U onto dashCopper tubingto hear knocking if no listening deviceExhaust manifold boltsto attach copper tubestethoscopelistening to engine noiseDefinitionsIn explosive detonation, the flame speed may be 2,500 to 3,000 feet per second (750-900 m/s) as opposed to 200 to 300 ft/s (60-90 m/s) for the norm

7、al burning rate.Octane: resistance to explosive combustion. alcohol, lead, manganese, humidity can increase octane.Key AdvantagesMaximum torque controlEngine runs on knock border lineFuel variationProtects engine from knock due to bad fuelOctane selectAuto selection of high and low octane, no switch

8、 input necessaryDigital knock controlProgrammable filterCylinder coordinated knockIncreases torque on small engines From MT20 presentation by Serge LambermontFuel economy and emissions also affected by spark.MBT Spark DeterminationFrom the GM Automotive Test Code, 1994Flat Response Knock Sensor Fami

9、lyCourtesy of K. MiuraSelf generating piezo-electric sensor with flat frequency response over range of 5-18 kHzVoltage output proportional to engine combustion intensityKnock sensor signalIRIC filtered signalIRIC integratorADESCIntegrator averageRaw Mean Average DeviationFiltered Mean Average Deviat

10、ionKnock ThresholdFast AttackFast RetardOctane ScalerAdaptive RetardSpark advance referenceIRICDetectionSpark controlGainIntegration constantIntegration constantMADFilter coefficientMultiplier calibrationsAttack and recoveryHigh/Low octane sparkWindowcenter frequencyESC Main FunctionsVibration Based

11、 System MechanizationPin 3 is the sensor outputPin 6 is the windowPin 4 is the integratorFrom the IRIC Application From IRIC application IRICMicroprocessoroscilloscopeFilter andamplifierKnocksensorRawsignalSensorgroundEST orCAMProcessed sensor signalwindowintegratorSPI Integrate and holdECMProcessed

12、 sensor signalSensorgroundMDSDUPCInstrumentationM/T Blazer on performance dynoKnock event at 5900 RPMMAP = 95 kPa (WOT)FFT is 5.00 kHz per division ( =50 kHz for the screen) +9 spark (from B2MT2203.cal)The system is effective at maximum RPM and load. By counting the signal peaks divided by the time

13、elapsed yields a frequency of 6.7 kHz. Conclusion: This shows that the window and center frequency are set properly.Blazer Knocking 5900 RPM, 95 kPa (WOT)Fast Fourier Transform (FFT)very high peak at 7 kHzKnock eventFFTsignalintegratorwindowsparkKnock sensor signal showing 11.5 kHz onlySGM 2.0L M/T

14、W-car with new pistonsKnock eventEST integratorSensorsignalwingate11.5 kHzFFTEST AwindowSensor signal(from IRIC)integratorKnock eventLarge integrator valueNormal combustionNormal combustionDong An 1.0L engineFrom Vibration-based knock detection cal procedureCenter FrequencyCaltools Center Frequency

15、CalibrationIRIC / OptionsInit gain, Q, CF, int constinitializationsWindowStart, durationGAIN controlUpper, lower, adjustment, maximumIntegratorADESCIntegrator averageRaw MADfiltered MADthresholdCo-efficientKnock presentIncreasing TPS RPMDecreasing TPS RPMSteady state TPS RPMKnock+RPM-RPM+TPS-TPSMaxM

16、inLoad compensationMAD multiplierTPSTimer, offsetPE compensationRPMTimer, offsetFilter co-efficientFiltering disableRPMTPSMAPTransient timeFiltering enableIRICECMThreshold CalculationIntegratorAverage = IntegratorAverage + (ADESC - IntegratorAverage) * MultiplierUpdating in “ESC_Event”When KnockPres

17、ent IntAveQ * K_Integratorfiltermultiplierelse IntAveQUpdating in 125msec loopConstantKnockThreshold = IntegratorAverage + noise_bandUpdating in “ESC_Event”noise_band = FilteredMAD * MADMultiplierFilteredMAD = FilteredMAD + (RawMAD - FilteredMAD)*K_MADFilterCoefficientUpdating in “ESC_Event”Constant

18、Updating in 15.6msec loopRawMAD = IntegratorAverage - ADESCUpdating in “ESC_Event”MT20 KNOCK DETECTIONCourtesy of Hiroshi UikeESCFastRetard = ESCFastRetard + ESCFastAttack*KnockLevelUpdating in “ESC_Event”KnockLevel = ADESC - KnockThresholdUpdating in “ESC_Event”ESCFastAttack = F_ESCFastAttack(RPM)Updating in 15.6msec LoopTable look upUpdating in “ESC_Event”RPM variable is updated in 7.81msec loopFAST RETARD CALCULATIONCourtesy of Hiroshi UikeIntegrator average (moving average of ADESC)Filtered Mean