1、In-Cylinder Analysis-1Rev.2004.10.22Cummins ProprietaryHSDA/Cell(High Speed Data Acquisition)Basic OverviewIn-Cylinder Analysis-2Rev.2004.10.22Cummins ProprietaryPrepared by:Bart L.Addis Link E.Brandon Lisa A.Farrell Keith Peterson John F.Wright Pete V.Woon Axel O.zur LoyeIn-Cylinder Analysis-3Rev.2
2、004.10.22Cummins ProprietaryPurpose of HSDA To acquire crank angle and time based engine data,such as:Cylinder pressure Other pressures,intake/exhaust manifold,EGR loop pulsations Push tube/rocker/link loadIn-Cylinder Analysis-4Rev.2004.10.22Cummins ProprietaryPurpose of HSDA(contd)Results are used
3、for:Combustion analysis(heat release,pumping,peak cylinder pressure,noise.)Injection analysis(SOI,injection P.)Limit diagrams Air handling analysis Transient responseIn-Cylinder Analysis-5Rev.2004.10.22Cummins ProprietaryWhy do we care?Electronics provide a high level of control over the engine Util
4、ize the in-cylinder data to establish operating boundaries,limits and to avoid catastrophic failures(reliability,durability)Insight into combustion processes Efficiency,performance,emissions optimizationIn-Cylinder Analysis-6Rev.2004.10.22Cummins ProprietaryWhat can we measure?Pressures Cylinder pre
5、ssure Manifold pressures Rail pressures Injection line pressures Injection pressure Strain gauge measurements Push tube load Rocker load Link load Specialty strain measurementsIn-Cylinder Analysis-7Rev.2004.10.22Cummins ProprietaryWhat can we measure contd?Needle lift RPM Vibration Torsionals Flame
6、arrival Spark timing Temperatures Any other voltageIn-Cylinder Analysis-8Rev.2004.10.22Cummins ProprietaryHSDA/CELL system description HSDA/CELL system is divided into two systems The data acquisition system,HSDA The HSDA system is responsible for all of the activities associated with acquiring the
7、data The post processing system,CELL The CELL system is responsible for post processing the dataIn-Cylinder Analysis-9Rev.2004.10.22Cummins ProprietaryHSDA system descriptionShaft encoderSignalConditioningA/D BoardsComputerSensor OutputEngineIn-Cylinder Analysis-10Rev.2004.10.22Cummins ProprietaryBa
8、sic Hardware Computer Monitor Keyboard A/D Boards Strain gauge amps Charge amps Shaft encoder Heat release interface UPS(uninterruptible power supply)In-Cylinder Analysis-11Rev.2004.10.22Cummins ProprietaryBasic System Limitations 16 analog channels 12 bits 50,000 samples per second(for 16 channels
9、with 4 A/D boards)200,000 samples per second(for 4 channels with 4 A/D boards)In-Cylinder Analysis-12Rev.2004.10.22Cummins ProprietaryCrank Angle Based Samplingvs.Time Based Sampling We need to know the position of the crankshaft for our analysis The shaft encoder tells the A/D when to take a measur
10、ement.that way we know what the crank angle is for each measurement.For comparison:an oscilloscope takes a measurement based on an internal clock.We would need a separate measurement to determine the position of the crank.It is possible to use the HSDA cart like an oscilloscope(running on an interna
11、l clock).In-Cylinder Analysis-13Rev.2004.10.22Cummins ProprietaryData Integrity Key decisions are made based on your data.Bad data leads to bad decisions.You can prevent bad data from being taken Acquire data from your baseline condition on a daily basis HSDA methods are available http:/ Analysis-14
12、Rev.2004.10.22Cummins ProprietaryWhats next now that you have your data?In-Cylinder Analysis-15Rev.2004.10.22Cummins ProprietaryUnderstanding In-Cylinder Data Objectives Develop a basic understanding of in-cylinder data analysis,what do we look at and why?Interpreting the data Acquiring high quality
13、 data Looking for bad dataIn-Cylinder Analysis-16Rev.2004.10.22Cummins ProprietaryOutlineWhy do we look at cylinder pressure data and what can we learn from the cylinder pressure data?What can we learn from the in-cylinder data?Cell software process flow Cylinder pressure Standard deviation Pegging
14、Log(P)Log(V)Log(T)plots Heat Release Data Flame and bulk temperatures EER,GIMEP,IMEP,centroid Specialty signals,push tube/rocker lever data Knock,EGT Efficiency improvementsEstimating the Intake PressureModifying the cutoff frequencyIn-Cylinder Analysis-17Rev.2004.10.22Cummins ProprietaryOutline Acq
15、uiring high quality data Pegging TDC shift Transducer installation/mounting Looking for bad data TDC setting Electrical noise Pegging Checking pressure transducer drift Transducer thermal shockIn-Cylinder Analysis-18Rev.2004.10.22Cummins ProprietaryHSDA/Cell Process FlowAcquire cylinder pressure dat
16、aCylinder pressure vs crank angleEngine speedLoadIMP/IMTFuel/air flowSpecialty signalpush tube,rocker arm,etc.Apparent heat release rate(AHHR)Cumulative heat release(CHR)dP/dqPeggingCELL Post Processing SoftwareEnd gas temperature(EGT)Flame temperatureEffective expansion ratio(EER)Centroid ReheatLog
17、(P)vs.Log(V)Bulk temperatureKnock intensitySpecialty signalsLog(P)vs.Log(T)Engine configuration/test cell informationGIMEPIMEPStandard deviationCOVCombustion noiseHSDA Hardware/SoftwareData acquired Data post processed in CELLIn-Cylinder Analysis-19Rev.2004.10.22Cummins ProprietaryCylinder VolumeThr
18、ow(R)Con Rod Length(L)Top DeadCenter(TDC)Bottom DeadCenter(BDC)Bore(B)Clearance Volume(Vc)q qDisplaced Volume(Vd)xThe instantaneous cylinder volume is defined by the following equationWhere q q is determined by the output from the encoder attached to the engine crankshaft.The engine configuration in
19、formation is input into the CELL configuration file.()()()5.02222csinRL+cosR=xandxR+L4B+V=VIn-Cylinder Analysis-20Rev.2004.10.22Cummins ProprietaryPegging Cylinder pressure signal is AC coupled This means that we know the shape of the signal and the relative amplitude of the signal.We do NOT know th
20、e DC offset(up and down placement)CELL slides the trace up or down(adjusts the DC offset)based on the intake manifold pressure.This is called pegging.It does this by assuming that the in-cylinder pressure at BDC compression equals the intake manifold pressure.In-Cylinder Analysis-21Rev.2004.10.22Cum
21、mins ProprietaryAn example of cylinder pressure peggingCyl prs is adjusted to equal IMP at BDC compressionCyl prs signal without peggingCyl prs signal with peggingIn-Cylinder Analysis-22Rev.2004.10.22Cummins ProprietaryPegging(cont.)There are different ways to specify the intake manifold pressure:Me
22、asured boost,input into Cell software Let CELL estimate it(2 ways)Pegging with crank angle sampled IMP is probably the best.In some situations it is advantageous to use the estimated pressure,instead of the measured intake manifold pressure.Most importantly,be consistent.In-Cylinder Analysis-23Rev.2
23、004.10.22Cummins ProprietaryPegging(cont.)Errors in pegging result in errors in:heat release calculations log(P)log(v)plots emissions estimates in-cylinder temperature estimates other calculations based on the cylinder pressureIn-Cylinder Analysis-24Rev.2004.10.22Cummins ProprietaryAcquiring good da
24、ta Transducer mounting Flush,preferred Recessed/passage mount Cooled,non-cooled Shaft encoder and TDC shift Pegging Intake manifold pressureIn-Cylinder Analysis-25Rev.2004.10.22Cummins ProprietaryCylinder pressure transducer mounting schemesAngled flush mount pressure transducer configurationFlush m
25、ount pressure transducer configurationPassage mount pressure transducer configuration.Not good for high fidelity measurements,like details of heat release rate.Flush mount is the preferred approach.Either of these configurations is acceptableCommunication passageIn-Cylinder Analysis-26Rev.2004.10.22
26、Cummins ProprietaryCylinder pressure transducer mounting schemes,contdKistler 6067 water cooled cylinder pressure transducer.In-Cylinder Analysis-27Rev.2004.10.22Cummins ProprietaryCylinder pressure transducer mounting schemes,contdPassage mounted cyl prs transducer for the 15L engine.In this specif
27、ic application the transducer is installed in the rear of the cylinder head.In-Cylinder Analysis-28Rev.2004.10.22Cummins ProprietaryCylinder pressure transducer mounting schemes,contd Rule of thumb Want highest natural frequency of the passage thats possible Want shortest possible passage length Wan
28、t the smallest cavity volume possible Want large passage diameter Typically,this is not possible and significant ringing resultsfrom passageIn-Cylinder Analysis-29Rev.2004.10.22Cummins ProprietaryShaft encoder and TDC shift Mounts to front of the engine with brackets Attaches to the front of the cra
29、nkshaft with a bellows assembly to accommodate angular mis-alignment The TDC pulse on the encoder must be radially aligned with primary pressure cylinder,typically TDC#1 firing course adjust(align by hand,using TDC lights on heat release interface)fine adjust(using CELL find Shift for TDC)THIS IS CR
30、ITICAL FOR ACCURATE DATA!Flexible bellows1440/2550 pulse/rev signal1 pulse/rev signal,TDCIn-Cylinder Analysis-30Rev.2004.10.22Cummins ProprietaryTDC shift(loss angle),contd Finding TDC from a motoring trace Peak cylinder pressure occurs before TDC(this is due to heat transfer)The angle at which peak
31、 cylinder pressure occurs(for a motoring trace)is called the“loss angle”For our engines,the loss angle at higher engine speeds is approximately 0.4 degrees BTDC.Follow method,TVV-TOP-0510.The method specifies RPM and boost The result is not very sensitive to boost,but the loss angle increases signif
32、icantly at very low RPM and if the engine is cold.In-Cylinder Analysis-31Rev.2004.10.22Cummins ProprietaryWhy do we measure cylinder pressure?Fundamental measurement that all in-cylinder analysis is based upon,must get this right!Tells one how well the engine is running(on that particular cylinder)A
33、llows us to assess data integrityIn-Cylinder Analysis-32Rev.2004.10.22Cummins ProprietaryCylinder pressure indicates The state of the combustion chamber pressure at a given crank angle Peak cylinder pressure(mechanical limit)Rate of cylinder pressure rise Start/end of combustion Combustion duration
34、Combustion noise Pumping loop work Engine knock Heat release shape,EER,centroidIn-Cylinder Analysis-33Rev.2004.10.22Cummins ProprietaryGraphical description of a cylinder pressure trace0500100015002000-60-40-20020406080100120Crank Angle(Degrees ATDC)Pressure(psia)-1.00.01.02.03.04.0Heat Release(rela
35、tive)Motoring pressureFiring pressurePressure rise dueto combustionHeat release rateCumulativeheat releaseInjection rateStart ofcombustionCombustion is very retardedIn-Cylinder Analysis-34Rev.2004.10.22Cummins ProprietaryBasic cylinder pressure as a function of crank angle plotCylinder pressure(psia
36、),3 channels in this examplePlot description and HSDA file nameDescription of signals/scales,engine operating conditionEngine crank angle scaleCyl prs increases due to decreasing volume,affected by CR and IMPStart of fuel injection/combustion indicated by“kink”in cyl prs.How can one verify the SOI?M
37、easuring prs at one point,average prs is smooth,locally have prs fluctuationsVariation in prs between cyls.Normal?Peak cyl prsIn-Cylinder Analysis-35Rev.2004.10.22Cummins ProprietaryLog(P)Log(V)cylinder pressureA Log(p)Log(v)plot is a graph of the cylinder pressure vs.the cylinder volume(which is a
38、function of crank angle)on a logarithmic scale.It allows us to examine the different parts of the cycle:Intake Compression Expansion ExhaustWe use this plot because we know that the compression stroke should be a straight line with a slope of approximately-1.35.This allows us to use the Log(p)Log(v)
39、plot for error checking.We can also examine out pumping loop work.In-Cylinder Analysis-36Rev.2004.10.22Cummins Proprietary1Experimental Log(P)-Log(V)Diagram7 82030 40 5060 80200100020304050608020030040050060080020003000101001000compressionEOIEVCIVOIVCEOCExpansionCombustionIntakeExhaustLog Cylinder P
40、ressure psiaLog Cylinder Volume in3CBDEFHGTDCBDCASOCSOIEVODescription of engine cycle and valve events A=Intake Valve ClosingB=Start of InjectionC=Start of CombustionD=End of InjectionE=End of CombustionF=Exhaust Valve OpeningG=Intake Valve OpeningH=Exhaust Valve ClosingIn-Cylinder Analysis-37Rev.20
41、04.10.22Cummins ProprietaryLog(P)Log(V)plot from a N14 engineClosed cycle and pumping loop pressures in(psi)The compression stroke should be a straight line with a slope of approximately -1.35.What would an incorrect CR input do to the slope?Incorrect TDC location?Log(P)(psia)Log(V)(in3)Remember thi
42、s is for one cylinderWhat causes the curvature?“Real”HRR.Need good quality data to analyze pumping loop data/lossesNoise,the result of valve seating eventIn-Cylinder Analysis-38Rev.2004.10.22Cummins ProprietaryHow sensitive is the slope of the Log(P)Log(V)curve to CR?CR has only a minor impact on th
43、e slope,but observe offset data compared to the baseline data.CR has no impact on the GIMEP.In-Cylinder Analysis-39Rev.2004.10.22Cummins ProprietaryHow sensitive is the slope of the Log(P)Log(V)curve to the TDC shift?Again,the TDC has only a minor impact on the slope,but observe offset data compared
44、 to the baseline data.The TDC shift has a significant affect on the GIMEP.A 0.1 shift in the TDC affects a 1%change in GIMEP.In-Cylinder Analysis-40Rev.2004.10.22Cummins ProprietaryHow sensitive is the slope of the Log(P)Log(V)curve to the IMP?The incorrect IMP has a small impact on the slope of the
45、 compression curve.Inspection of the pumping loops reveals that IMP has a significant effect.In-Cylinder Analysis-41Rev.2004.10.22Cummins ProprietaryHow is the Log(P)Log(V)curve affected by pegging?Turning off the cylinder pressure pegging is a“bad thing”,dont do it!In-Cylinder Analysis-42Rev.2004.1
46、0.22Cummins ProprietaryWhat should the compression slope be?Effect of EGR on ratio of specific heats(gamma).Diesel,A/F=25.4,phi=0.575.1.281.301.321.341.361.381.401.4230040050060070080090010001100Temperature(K)C_p/C_v (gamma)80280480680880108012801480Temperature(F)0%20%40%EGR100%100%EGR line drops an
47、other 0.01 at phi=1(stoich)In-Cylinder Analysis-43Rev.2004.10.22Cummins ProprietaryAdditional Log(P)Log(V)information Gross indicated mean effective pressure GIMEP(closed cycle calculation,combustion)Pumping mean effective pressure PMEP(pumping loop,fluid exchange process)NIMEP=GIMEP+PMEPFMEP=NIMEP-
48、BMEP(Use coast down method to measure FMEP,TVV-TOP-0486)3inVolumelbsftTorque*8.150=BMEP-In-Cylinder Analysis-44Rev.2004.10.22Cummins ProprietaryAdditional Log(P)Log(V)informationFor example,FMEP data on the Cat C15 engine tested at CTCTest methodFMEP (psi)Coast down16NIMEP-BMEP21.2The coast down met
49、hod provides superior resultsIn-Cylinder Analysis-45Rev.2004.10.22Cummins ProprietaryWhat do heat release rates(HRR)indicate?What is a heat release rate?The heat release rate tells us how fast the fuel is burning.Apparent heat release rate(AHHR)The apparent heat release rate is calculated from the c
50、ylinder pressure.It tells us how fast energy is added(or released)to the gases in the cylinder.The difference between the heat release rate and the apparent heat release rate is heat transfer.Heat transfer to the coolant,piston,liner and cylinder head HRR rate is also affected by the blowby or gas l
