D N s
`1;: A E T n A N s
`\
`'
`‘
`""931 .
`3
`J. C. Ellis/President M. J. Kittler/Treasurer
`Joseph Gilbekt/Sec_re‘tafry_‘énd General Manager _
`., ._...—
`—_
`
`PUBLISHED BY SOCIETY OF AUTOMOTIVE ENGINEERS,
`
`INCJTWO PENNSYLVANIA PLAZA/NEW YORK, NY. 10001
`
`Page 1 of 18
`
`BOSCH-DAIMLER EXHIBIT 1013
`
`

`
`L_b © Society of Automotive Engineers. Inc., 1973
`'
`raw of Congress Catalog Card Number: 1244937
`Printed in U.S.A.
`
`Page 2 of 18
`
`

`
`TABLE OF CONTENTS
`
`Papers 7204473120743
`
`An Investigation ofThermaI Conditions Leading to Surface Rupture of Cast Iron Rotors4RudolfLimpert
`
`Radioisotope Reveals Behavior of Lubricants in Two-Stroke Cycle Engines»—-Tait ashi Kohayalcawa, Yoshimi Hirai,
`Tsugio Ogawa, and Eizi Suzuki
`
`A Screening Tool for Outboard Motor Fuels and Lubricants—W. R. Pyle
`
`Transient Engine Testing by Computer Control—J. F. Cassidy, Jr., and J. H. Rjllings
`
`A Comparison of Dynamic Exhaust Emissions Tests: Chassis Dynamometer versus Engine Dynamometer—J. F.
`Cassidy, Jr.
`
`Professional Ethics and Environmental Technology—M. R. J. Wyllie
`
`Improvements of the Rotary Engine with a Charge Cooled Rotor—Kojiro Yamaoka and Hiroshi Tado .................. ..
`
`Specialized Road Surfaces for Traction Test Purposes—C. V. Allen and F. D. Smithson
`
`Testing and Analysis ofTire Hydroplaning~—R. W. Yeager and J. L.Ttltlle
`
`A New Laboratory Facility for Measuring Vehicle Parameters Affecting Understeer and Brake Steer—A. L. Nedley
`and W. J.Wilson
`
`Status Report on HC/C0 Oxidation Catalysts for Exhaust Emission Control~P. W. Snyder. W. A. Stover, and H.
`G. Lassen
`
`NO. Reduction Catalysts for Vehicle Emission Control—G. H. Meguerian, F. W. Rakowsky, E. H. Hirschberg, C.
`R. Lang, and D. N. Schock
`
`Methods for Fast Catalytic System Warm-Up During Vehicle Cold Starts—W. E. Bernhardt and E. Hoffman
`
`Economical Matching of the Thermal Reactor to Small Engine—Low Emission Concept Vehictes—l-I. Kuroda, Y.
`Nakajima, Y. Hayashi, and K.Sugihara
`
`Metal Foams as Energy Absorbers for Automobile Bumpers—-L. M. Niebylski and R. J. Fanning
`
`Development and Analysis of Door Side—ImpactReit1forcements—-John S. Haynes
`
`Crash Data At-|alysis—G. G. Lim
`
`Automotive Lamp Outage Dc,tection—F_ J.
`
`Interior Window Fogging—An Analysis ofthe Parameters Invo]ved—Alexander R. Peters
`
`A Systems Approach to Vehicle Emission Control—E. N. Cantwell, R. A. Hoflmau, I. T. Rosenlund, and S. W.
`Ross
`
`Field Test of an Exhaust Gas Recirculation System for the Control of Automotive Oxides of Nitrogen-—John C.
`Chipman, John Y. Chan, Ray M. Ingels, Roy G. Jewell, and WCndC1lF- D3318!’
`
`Designing Clad Metals for Corrosion Control——Robert Baboian
`
`Aluminum Striped Stainless Trim for Prevention ofAuto Body Galvanic Corrosion—Jack M. Beigay and Donald R.
`Zaremski
`
`Analytical Evaluation of a Catalytic Converter System—John L. Harned
`
`Air Frcigh1_Pa_y5 Of-fin P;-ofi[5.—L_ I)_ Richardson
`
`The Day's News Goes to Market on Night Flights—Edward F. McDougal
`
`Handling Intermgdal and Interline C0m_3[ncr5—Greg0ry V. Schultz
`
`Removing Roadbiocksl from International Customs Clearance—John 3- 0'1-0|-Igl'|llIl
`
`The Development of Personal Rapid Transit—Albert J. Sobey
`
`720447
`
`720450
`
`72045 I
`
`720454
`
`720455
`
`720462
`
`77.0455
`
`720469
`
`' 720471
`720473
`
`720479
`
`720480
`
`72043 1
`
`7204-34
`
`720490
`
`720494
`
`720496
`
`720501
`
`720503
`
`7205 10
`
`7205ll
`
`7205}-'-l
`
`720515
`
`720520
`
`720531
`
`720532
`
`720533
`
`720537
`
`720553
`
`Page 3 of 18
`
`

`
`720579 Flexible Wings for Transportation—Francis M. Rogallo. liarned
`720531 Air Freight Pays Offin Profits~—L. D. Richardson
`720532 The Day's News Goes to Market on Night Flights—-Edward F. McDougal
`720533 Handling Intermodal and Interline Containers~Gregory V. Schultz
`720537 Removing Roadblocks from International CustomsClearance—John B. O‘Loughlin .............................................. .-
`720553 The Development of Personal Rapid Transit-—Albert J. Sobey
`720579 Flexible Wings for Transportation—Francis M. Rogalio. Delwin R. Croorn, and William C. Sleern an, Jr. .................
`720581 Civil Applications oftheAir Cushion Landing System—David l-l. Grupe
`720593 The Development of Propulsion Systems for Air Transport—Harry Pearson
`720610 The Impact ofAircraft Emissions Upon Air Quality—Melvin Flatt and E. Karl Bastress
`720611 Monitoring and Modeling of Airport Air Pollution—D. M. Rote, I. T. Wang, L. Wangen, J. Pratapas, Lois Lefiler,
`and GlenCato
`
`720621 Aircraft Noise and the Airlines—-William B. Becker
`720627 Consideration of Environmental Noise Effects in Transportation Planning by Governmental Entities~—Louis H.
`Mayo
`720630 Ecologic Ramifications ol'Air Pol1ution—Harvey Babich and Guenther Stotzkv ..................................................... ..
`
`720636 Origins of Diesel Truck Noise and Its Control—-P. E. Waters and T. Priede _____________________________________________________________ __
`
`720669 Selection Moclels—Small Truck Fleets—J. C.Selby
`
`720670 The Boston Reformed Fuel Car—Marc S. Newkirk and James L. Abel
`720677 Guidance of Vehicles by Telecomrnand in Order to Simulate Aecidents—-Harald J. Schimkat, Erich W. Unterreiner,
`and Riidiger W. Will
`
`720686 Interactions Among Oil Additive and Engine Operating Parameters Affecting Engine Deposits and Wear—Loren G.
`Pless
`..
`...
`
`720639 Unleaded Gasoline~—l.ubrieant Requirements and Fuel Additive Perform ancerD. S. Orrin W. R. Miner and K L
`
`720691 New Choice in Excavating with a Hydraulic Digger——Char1es L. Fleming and Alan S. McC|imon
`
`720692 Engine Performance and Exhaust Emissions; Methanol versus Isooetane—G. D. Ebersoie and F. S. Manning
`
`720693 Exhaust Emissions from a Methanol-Fueled Autom obi]e—H. G. Adelman, D. G. Andrews, and R S Devoto
`
`720707 On the Noise Reduction ol‘ a Rectangular Box with Application to Tractor Cabs—M G Milsted and E L Wegs
`cheid
`..
`I
`I
`I
`‘
`
`-
`
`720703 Torque Sensing Variable Speed V-Belt Drive—Larry R. Oliver and Dewey D Henderson
`
`720710 Driveline Torque Coupling for Tractor Draft Control—C. E. McKeon
`"
`.-.nrge,an..
`720719 Sound Level Tests of Agricultural Tractors—W E Splinter M L Mumgaard G W Stei b neg
`d L F
`Larsen
`720724 Characteristics of Multiple Range HydromechanicalTransmissions Eliflrshansky and W'll'
`E W 1 h
`H
`H
`_ —
`1 ram .
`ese 0
`......... ..
`rzorzsa
`1119-
`.
`--
`-
`-
`,
`PPYOHC 55 0
`951311 0? Low Emission Gas'1'urb1ne Combustion Chambers—Donaid M. Dix and E. Karl Bastress ..
`
`~
`
`720731 Determ'
`'
`C " lwh’
`Mom” Crankshaft FIYWTIEBI Assemb13'~Robert T. Larsen and
`Arthur l§::.EnS(::fCjE:__
`720739 New Bearing Concepts for Gas Turbines—Elie B Arwas John M MCG
`d |_ w w i
`r
`-
`YEW. an
`co
`.
`inn ............................... ..
`'
`720740 Lo\v—Cost Fluid Film Bearings for Gas Turbine Engines—J M Ross
`720743 Traction and Flotation Ch
`1
`‘
`t‘
`f
`A
`-
`'
`.
`-
`arac ens rcs o Earthmover Tires on Soft So1]—Masat0sh1Satalce and Tsunco Mukai
`
`Page 4 of 18
`
`

`
`Methods for
`
`Fast Catalytic System Warm-Up
`
`During Vehicle Cold Starts
`
`W. E. Bernhardt and E. Hoffmann
`Volkswagenwerk AG
`
`TO ACHIEVE the emission targets prescribed by law for
`1975-1976 a number of emission concepts with conventional
`internal combustion engines and emission control systems
`have been examined by the automotive industry. Catalytic
`converters, thermal reactors, and a combination of these two
`have been considered as emission control systems (I)*. Low
`emission values have been attained with these concepts when
`the engine is under warm working condition. However, the
`difflculties lie mainly in the warmup phase during cold vehicle
`startup.
`
`To improve the overall effectiveness of catalytic systems at
`vehicle startup, extensive experimental tests were carried out
`during the warmup phase on various afterburning systems by
`the Research Department of the Volkswagenwerk AG. The
`intent of this paper is to illustrate the utility of improving the
`
`‘Numbers in parentheses designate References at end of
`paper.
`
`warmup characteristic of catalytic emission-control systems
`for achieving very low emission levels.
`
`WARMUP METHODS FOR CATALYTIC SYSTEMS
`
`Catalytic emission-control systems described in this paper
`operate mainly with the dua.l—bed catalytic process. The first
`bed contains the reduction catalyst which reduces the oxides
`of nitrogen (NOX) by carbon monoxide (CO), hydrogen (H2),
`and hydrocarbons (HC) which are present in the exhaust
`gases. The reaction between NOX and CO will only take
`place providing that the amount of oxygen (02) present in the
`exhaust gas is strictly limited to low concentrations. This
`oxygen limitation is met by adjusting rich fuelfairimixtures.
`The second catalyst bed contains the oxidation catalyst
`which burns the C0 and HC after introducing secondary air
`between the first and second beds. The quantity of secon-
`
`ABSTRACT _‘j,
`throttle. Intensive studies to investigate the effects of con-
`current changes ofspark timing and airffuel mixtures an
`exhaust gas temperature, enthalpy, NO and HC emissions are
`discussed.
`X
`
`Catalytic exhaust-control systems must be designed to op-
`erate at high efficiency almost from the moment of engine
`startup. Catalysts must reach their operating temperature as
`quickly as possible. Therefore, the utility of different meth.
`ods for improving the warmup characteristics of catalytic sys-
`tems is illustrated.
`.
`A very elegant method to speed the warmup is the use of
`the engine itself as a “preheater" for the catalytic converters.
`High exhaust gas enthalpy to raise exhaust system mass up to
`its operating temperature is obtained by the use of extreme
`spark retard, stoichiometric mixtures, and fully Opened
`
`Finally. NOX catalyst characteristics are dealt with, because
`the NOX catalyst is the first in a dual-bed catalytic system.
`The Nox Catalyst should have high activity, low-ignition
`l"—'mPBfat11Ie, and good warmup performance. If the NOX
`¢3l3lY5t has a fast warmup rate, this would result even in a
`Significant improvement in the wannup characteristic of the
`HCl'CO bed.
`
`1654
`
`Page 5 of 18
`
`

`
`dary air is set high enough to ensure that there is excess
`oxygen for all driving conditions.
`Fig. 1 illustrates a dual-bed axial-flow converter. Such a
`concept, using fresh catalysts when tested according to the
`CVS cold-hot test procedure, gave emission values which were
`still twice as high as the exhaust emission standards specified
`for model year 1976. The results would be considerably
`better if the catalytic emission system could be warmed up
`very quickly from the moment of cold engine startup.
`Methods to speed the warmup are:
`1. Reduce the heat capacity of the exhaust system between
`the engine and the dual-bed converter.
`2. Reduce the heat capacity of the catalyst, use smaller
`catalyst quantities, and smaller catalyst particles.
`3. Mount the converter very near to the engine exhaust
`valves.
`
`4. Introduce secondary air in front of the first bed during
`the initial I20 s after cold engine startup; then switch the
`
`secondary air to the connecting pipe between NOX and HC;'
`C0 beds (staged secondary air).
`
`Even when these features were used, the dua.l—bed system
`illustrated in Fig. 1 could not reach the targets of 0.41 g HCI
`mile, 3.4 g C0.r'rnile, and 0.4 g Noximile, as proposed in the
`Federal Register for 1976.
`
`It is particularly difficult to fulfill the emission standard for
`oxides of nitrogen as the temperature in the NOX bed increases
`very slowly in systems which are designed to allow an ade-
`quate residence time for the exhaust gases. Fig. 2 illustrates
`the mid-bed temperature of a VW radial-flow converter with a
`1.3 litre NOX bed during the CVS cold start. It is plain to
`
`see that the catalyst ignition temperature of approximately
`250 C was reached in the pelleted NOX catalyst bed after 195 s
`in spite of the use of the staged secondary air feature. The
`ammonia problem can also be seen in Fig. 2, although this is
`
`INSPECTION HOLES
`
`LDUVER PLATE
`
`EXHAHST
`GAS OUT
`
`EXHAIJST
`
`HCIED CATALYST BED
`
`HUICATALYST EEO
`
`WSECEIIIUARY AIR
`
`Fig. 1 - I)uel—bed catalytic converter (axial flow)
`
`vw M’ urea rrrps U.
`
`aacw. now own. BED CONVERTER. PELLETEO CAFMYSVS
`
`sscauoam am smrcuso to
`" ""'aérwE£rv 'sEc'r5'
`‘E-‘fifiif SPEEQ
`
`'
`
`'
`
`I
`
`‘
`'
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`_
`F1g- 2 - N03: ‘hid-bed temperature and °°"°°“‘”“‘°"
`
`during cold-start portion of CVS test
`
`TIRE‘ SEC.
`
`1655
`
`Page 6 of 18
`
`

`
`1656
`
`W. E. BERNHARDT AND E. HOFFMANN
`
`d
`
`.
`.
`.
`.
`_
`-
`not bemg dealt with "1 this Camacho“. For more detafle
`information refer to Ref. 2.
`f
`a]
`-
`X1
`{emission
`To illustrate the problems o cat Y1“? 3 W15
`'
`.
`-
`-
`*
`11
`control systems, Flg. 3 shows the tail PIP'32:311ss1?nsCa\:;J:ol§‘S
`the exhaust gas flow me during the fidstth
`:3: flow rate
`start test. Both the concentrations an
`e In
`f
`.
`d d
`.
`th CV5 cold start test
`vary by orders 0 magmtu e unng
`e I
`-
`procedure. Furthermore, the concentratrons of CO and HC
`
`,
`
`'
`'
`-
`80 s. For this reason
`a e articularly hrgh during the first
`c:taIl)ytic emission-control systems must be designed to
`operate with high efficiency, that means high reduction and
`_
`. kl
`me after the en me
`conversion rates, as quic y as possr
`g
`Startupi The Catalysts Should reach their Operating tempem.
`tures within 20 s so that the emissions which are produced
`'
`during the warrnup period of the engine can be controlled as
`_
`_bl
`quickly 35 P0531
`‘*-
`
`u-§w:c;_£ vw rrPE it r7urE-9 EN-SW5
`porn L090
`3500
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`“GI 2:130
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`I50
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`200
`
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`
`40
`
`80
`
`‘I20
`
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`see.
`an onvorzs one rm mare. smwnrvo cum: METER PER mvurz
`Fig- 3 - Cold-start raw emissions in comparison with vehicle speed and exhaust gas flow rate
`
`SEIZDNDARV AIFI INJECTIIIN
`
`5 ECHNDARY AIR PUMP
`
`EGR rm-use vnwe
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`CONVERTER
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`Fig. 4 - Combined reactor-EGR.
`
`catalyst system major hardware components
`
`Page 7 of 18
`
`

`
`CATALYTIC SYSTEM WARM-UP
`
`1657
`
`To do this, further methods for improving the warmup
`characteristics of dual~bed systems should be investigated.
`One method which promises success is a thermal reactor
`acting as a “preheater” for improving catalytic converter
`performance. The thermal reactor is located at the cylinder
`heads. When starting with a rich fuelfair mixture, oxidation
`of C0 and HC after adding air, ensures rapid warmup of the
`catalyst.
`In this system, secondary air is introduced in front
`of the thermal reactor at the cylinder head, and the reduction
`
`catalyst works as an oxidation catalyst in the starting phase.
`Due to the burning of high HC and CO emission levels directly
`after stsrtup a rapid warmup of the afterburning system and
`therefore a rapid attainment ofoperating temperature is
`ensured.
`
`A catalytic reduction of NOX is not necessary during the
`
`cold-start phase because the engine operating temperature
`during this period is not high enough to produce very high
`NOX emissions. After the catalysts in both beds have reached
`their operating temperatures (100-I 20 s after CVS cold
`startup), the thermal reactor must be switched off. This is
`brought about by the transfer ofsecondary air introduction
`to the connecting manifold between the first and second
`catalyst beds.
`Fig. 4 illustrates a catalytic emission-control system,
`together with major hardware components, which has been
`developed for research purposes. It consists of a monolithic
`dual-bed converter, seriesconnected thermal reactors, bypass
`system, exhaust gas recirculation (EGR), EGR cooler,
`regulating valve, and EGR filter. The efficiency of such an
`emission-control concept can be improved by the introduction
`of an additional ignition system in the thermal reactor. By
`enrichment of the airlfuel mixture, an improvement can be
`obtained, as can be seen in Fig. 5. With 10% rich fuelfair
`mixtures (AIF = 13.0), the exhaust gas temperature at the
`thermal reactor outlet reaches 300 C 5-6 s earlier than with
`normal mixture strength (AIF = 16.0).
`This high exhaust gas temperature increases the reactor
`warmup rate, too. This means that the catalysts also reach
`
`their operating temperatures of about 300 C at least 5 s
`earlier.
`
`Another method ofimproving the warmup rate of the
`catalytic system with series connected thermal reactors is to
`cause an ignition failure of a single cylinder charge (which
`contains approximately 20,000 ppm HC) and at the same time
`to increase the idling speed of the engine together with wide
`open throttle (WOT). The technique produces an increased
`flow rate of exhaust gases with high unburned components
`during the cold-start phase; the chemical energy of which can
`be converted into high exhaust enthalpy. This comparatively
`rich fuetfair mixture can be ignited in the reactor by an
`additional spark plug. With an automatic control device, the
`ignition failure of a particular cylinder can be controlled in
`accordance with the firing order. After the exhaust gas has
`attained the operating temperature required by the catalysts
`the ignition system will revert to normal.
`Fig. 6 shows the results of an engine cold-start test employ-
`ing this warmup system. The illustration shows the time
`dependence of the exhaust temperature in the reactor core
`and at the reactor outlet as a function of throttle opening.
`The test was carried out at an engine speed of 2800 rpm. The
`throttle valve angle was increased from 5 to 35 deg. A
`maximum speed governor controlled the ignition failure. It
`can be seen in Fig. 6, for example, that with a throttle valve
`opening of 35 deg a reactor outlet temperature of 360 C is
`achieved in 10 s. Even when considering the heat loss of the
`
`‘CID CU IN 'lHERM1L HEJICTOE WWH ADDIHDNAL IGNITION SYSTEM
`lfl THE REflC-TOR. WKU W':lRM"I.l'P SPARK RETIRE
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`Fig. 5 - Influence of rich airffuel mixture on reactor outlet temperature
`for better system warmup
`
`an cum THERMAL nrncron WITH sr-Anicrtucsm rH£
`INLET mars, IDLE srrro am am, rcmmolv FAILURE
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`Fig 6 - Effect of controlled ignition failure on reactor warmuP 35 3 f'-‘“°“°“ °f ‘l"°"l° °P°“l“3
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`
`Page 8 of 18
`
`

`
`1658
`
`W. E. BERNHARDT AND E. HOFFMANN
`
`exhaust system between the thermal reactor and the catalytic
`system, it can be ensured that the operating temperature of
`the first bed can be reached in a very short interval of time.
`Especially when operating under rich fuelfair conditions
`with thermal reactors mounted at the cylinder heads tempera-
`tures could be produced which are above the melting tempera-
`ture of the monolithic materials, such as Cordierite (Mg2Al4-
`
`$5013), Mu1lite(3Al2O3 - 23:02), and at-Alurnina(orA12O3).
`In Fig. 7, the monolithic catalyst reached temperatures of
`more than 1350 C. It can be seen by the figure that the
`center of the monolithic catalyst has been melted when
`operating together with a front-mounted reactor. Tests have
`proved that a too high inlet concentration of HCKCO is not the
`cause of this high bed temperature. The cause of the thermal
`destruction of the material could lay in the unequal distribu-
`tion of the active components on the support materiai. This
`unequal distribution of material, as for example Cut), could
`have led to a drastic reduction of the melting temperature
`from 1350 down to 975 C. Similar symptoms in the outer
`coating were observed during the aging process of catalysts by
`J. F. Roth (3).
`In place of the thermal reactors, monolithic noble metal
`catalysts could be empioyed as warmup elements because the
`majority of the HC and C0 emissions produced by an
`engine are emitted in the first 2 min of the '23 min CVS cold-
`
`hot test, while the NO)‘ emission in general is produced over
`the whole test period. For this reason, a monolithic HCICO
`converter at each side of the engine which reduces the high
`CO and HC raw emissions with high efficiency could be used
`to improve the warrnup characteristic. Due to the good cold-
`start performance and the low ignition temperature, the
`platinum monolith is particularly suitable. The ignition
`temperature for C0 is approximately between 200 and 230 C
`and for I-IC (hexane) between 240 and 340 C.
`To give a complete presentation of warrnup possibilities,
`other more sophisticated methods for rapid warmup of
`catalytic systems should be mentioned.
`One such approach involves the use of a gasoline heater; the
`other approach involves an electric heater. An electrically
`heated HCICO radial-flow converter in which high temperature
`resistance heating rods were installed was tested within the
`IIEC program (4). These heating rods were capable of heating
`the first layer of the catalytic bed (approx. 0.5 lb) from the
`ambient temperature to 300 C within 30-40 s at startup.
`Power requirements were available from vehicle electrical
`system. Similar results were obtained by the VW Research
`Department with pelleted catalysts in axial-flow converters
`which were, however, supplied by an external electrical
`system. The power available from the battery alone was not
`sufficient.
`
`In most cases the gasoline heater has the disadvantage of not
`being able to operate against the relatively high exhaust gas
`back pressures. A further disadvantage is that an auxiliary
`heater could produce considerably high emissions. Without
`taking the engine emissions into consideration, the values
`produced during a CVS test by a particular heating system
`were: HC, 0.58 glmile; CO, 0.42 gin-rile; and NOX, 0.03 g)‘
`mile.
`_
`
`it may be surprising that for HC this is more than 40%
`above the 1975 target, while the C0 emission is approx. 12%
`and the NO,‘ emission is approx. 8% of the emission standards
`proposed for 1976. Fortunately, a properly designed gasoline
`heater operating only 100-120 s after engine startup has
`considerably lower emissions.
`Another method of improving the initial reaction tempera-
`ture of the catalytic system is to increase the exhaust gas
`l3mPeI31l-Ire by altering the ignition timing into the region
`after tdc. By the use of extreme retarded timing at vehicle
`5:311’-‘P. for example, the catalyst operating temperature of
`250 C was reached 25 s earlier in the CVS test than by normal
`ignition timing. The influences of ignition timing on the
`combustion P100358 (exhaust gas temperature and exhaust
`gas emissions) are discussed in more detail in the next sec-
`tion. Based on extensive single cylinder measurements the
`“lint? Of this vvarmup technique is illustrated because of its
`P3“lC“13Ti1T1P0Tt3fl¢8 for speeding the warrnup performance Of
`Catalytic systems.
`
`Fig. ‘I - Monolithic catalyst failure during rapid war-mup pm-ormanoe
`
`only _bY 31'!‘-P10Yi1‘1g afterburning systems can the extremal)’
`low emission targets for model year 1975-1976 he reached.
`
`WARMUP TECHNIQUE BY SPECIAL ENGINE OPERATION
`
`Page 9 of 18
`
`

`
`CATALYTIC SYSTEM WARM-UP
`
`1659
`
`case of extreme retarded timing the maximum pressure is
`reduced from 16.5 - 105-7.8 - 105 Pa at 20 and so deg atc,
`respectively. The expansion process of the working lluid can
`be noticed very late, runs at comparatively high pressure level,
`and, due to the opening of the exhaust valve, it is cut off at a
`high pressure. Due to this energy loss to the ambient (that is,
`loss of the work done on the piston) the indicated mean effec-
`tive pressure was reduced from 330- 105-3135 - 105 Pa. This
`result can be taken directly from the energy release diagram
`(lower diagram).
`Due to the late energy release rise, the period in which the
`high temperatures are produced in the exhaust gases is
`considerably shortened. For this reason the heat loss to the
`cylinder walls during combustion is less. The same quantity of
`fuel is converted into energy in both cases, but in the case of
`
`extreme spark retard the piston work Li and the heat loss to
`
`the walls Q“, = QB — OH is reduced, and the internal energy of
`
`the working gases Ui = QH - Li is increased by the appropriate
`amount. The exhaust gas temperature is thereby increased by
`
`II No Work W12 ls Done By The Engine The Sensible Heat C112
`Reaches Its Maximum
`
`Therefore, one of the most important tasks of the internal
`combustion engine is to ensure high efficiency almost
`immediately after engine startup by changing the engine
`conditions especially for this requirement. it has been found
`that under appropriate operating conditions the engine itself is
`able to act as a preheater for the catalytic system. Warmup
`spark retard and an increased idling speed of the engine with
`full open throttle lead to higher exhaust temperatures and
`thereby to a greater enthalpy of the exhaust gases, so that the
`afterburning system could be brought rapidly up to its
`operating temperature.
`Fig. 8 shows schematically an internal combustion engine as
`an open thermodynamic system. If steady flow is assumed,
`the application of the first law of thermodynamics gives
`important information about possibilities of increasing the
`exhaust gas enthalpy (see Figs. 8 and 9).
`I
`As shown in the equations in Fig. 9 the total chemical
`energy of the exhaust gases can be used to increase the
`exhaust gas enthalpy if the shaft work is zero (W12 = 0). In
`practice, this operation condition cannot be achieved because
`the engine could not overcome its own mechanical friction.
`The maximum heat of the exhaust gases (Ql2)max is, there-
`fore, not at the no work condition, but at an indicated output
`which is appropriate to the mechanical friction of the engine.
`A second factor is the quantity of the exhaust gas flow rate
`which can be increased by opening the throttle.
`In an engine,
`the condition W12 = 0 can be attained by altering the ignition
`timing to “retard.” in this case, the energy release rises very
`late so that the work done on the piston becomes less.
`To illustrate the influence of the ignition timing on the
`combustion process more clearly, Fig. 10 should be con~
`sidered. This figure illustrates the results of a therrnodyn amic
`analysis of two combustion processes at low load. The com-
`bustion cycles differ only in the ignition timing (9 deg into as
`opposed to normal adjustment of 27 deg btc) whereas other
`engine parameters such as air,’ fuel ratio (AIF) and volumetric
`efficiency remained equal. Essential differences can be seen
`already in the pressure-time history {upper diagram). In the
`
`U pen Steady- Flow System
`
`w12=|J—~»—-- t'112=I-‘rill-:2-h1+tr.[\o'_-.g?—-\I12ll
`i‘11g=:ia[h2+9'»V23-ha}
`v;
`= rh I 1 A2 -9 21:
`:9—l'.|E|\|SlTY
`,;13
`I hz-ha I + ‘I: Hafiz):
`
`2
`V‘
`'1: = 311 + T.
`
` -—I‘
`AEUUTLET AREA,
`
`l1|2= ii:
`
`up zip it):
`
`t—'I'EMi’:
`
`I39-SPECtF||2 HEAT .fiT CONSTANT PRESSURE
`
`rfia
`fi|2= rialfipltg-1gl+ ‘./zmzlpzlz
`
`l5AME SYMBOLS ASIN FIGURE 81'
`
`Fig. 9 - Application of first law of thermodynamics to increase sensible
`heat of exhaust gases
`
`r'112_Hear, W13--WORK, rir—MASS new RATE”, r...smrH.3LPv
`PER umr MASS, v—veLor:I'rv,susscanPr 3- amsisrar .
`
`Fig, 3 - Application of first law of thermodynamics to an internal
`combustion engine
`
`Page 10 of 18
`
`

`
`1 660
`
`W. E. BERNHARDT AND E. HOFFMANN
`
`66 C from 580 to 646 C. The exhaust gas emissions are
`thereby also strongly influenced; the HC emission is reduced
`from 132 to 60 ppm by the high exhaust temperature, and tlte
`NOX emission is suppressed from 1888 to 720 ppm due to the
`retarded ignition timing.
`_
`For the experimental investigation a VW 1.6 litre, single
`cylinder engine with a production type combustion chamber
`was used. A mechanical fuel injection system was chosen with
`which optimum fuel} air ratios, good mixture preparation, and
`an independence from the distributor setting was available.
`The measurement of the exhaust gas temperature was
`carried out in the exhaust with an insulated thermocouple of
`LS mm OD. The holding device for the thermo-element was
`fitted with a radiation shield.
`
`The tests began with an increased idling speed of 2500 rpm
`and were later continued at 1500 rpm. The engine speeds
`were selected with respect to the highest possible exhaust flow
`rate. After adjusting the ignition timing the individual measur-
`ing points were chosen to a particular value in relation to the
`airflow rate, while the required A,"F was regulated by the fuel
`quantity. Deviations from the mean effective pressure
`(mep) = 0 had to be balanced out by adjusting the supplied air
`and fuel flow rates in stages.
`In addition to the measured exhaust gas temperatures, Fig.
`11 shows the HC and NOX emissions as well as the exhaust gas
`
`enthalpy as a function of AKF and ignition timing. These
`results are in good agreement with the theory. As expected,
`the exhaust gas temperature increased very rapidly when the
`ignition timing was retarded to a region after tdc. However,
`due to alteration of the ignition timing, the indicated output
`was decreased, as already mentioned. In order to keep the
`engine running the cylinder charge was repeatedly increased as
`the timing became more retarded until finally the throttle was
`fully open. Therefore, the wide open throttie limit in the ig-
`nition region after tdc is given as the left-hand limit on the
`performance diagrams of Fig. 11. The highest temperatures
`measured at the WOT limit were 794 C at the engine speed
`of 1500 rpm and 912 C at 2500 rpm. The limit with spark
`
`advance is dependent on the AIF in the same manner as it
`is with spark retard. However, the criterion for thislimit is
`not the throttle opening but the breakdown of the combus-
`tion cycles which results in a rapid increase of the HC emis-
`sion.
`
`The exhaust gas temperature diagram in Fig. 11 iilustrates
`the influence of the AIF and the ignition timing on the ex-
`haust gas temperature. The exhaust gas temperature reaches
`its maximum at a reciprocal equivalence ratio of lfqb = 1.0
`because the combustion temperature is highest at stoichio-
`metric mixtures.
`
`The increase of AIF at a constant spark advance brings the
`exhaust gas temperature up to a maximum at greatest possible
`AXE‘.
`This is explained by the postponement of the combustion
`process into the expansion stroke which is, in turn, caused by
`the lower flame speed at lean mixtures. Furthermore, the
`volumetric efficiency increases as the Al F becomes larger.
`The low exhaust temperatures at rich mixtures are attributed
`to the cooling effect of the fuel in very rich mixtures. In
`
`'lHRO'lTLE ii]! US1 ME N ‘I’
`XHMET GAS
`IE!-IPERATL.I?E-C
`
`IH #051 5A5
`EN!'HhLF"f-kou
`
`
`
`REEIPRUCALEOLII|mI.ENCERIITIO
`
`FiE- 11 -Engine Warmup performance test. Engine speed 1500 rpm.
`steady-state, no load
`
`1b
`T
`cm: Rivets
`
`roercso
`DEBREE
`
`SFNGEE CYLINDER ENGINE. vw 1.6 LITEH wiru MECHANIEAL rust Iriireriau
`ENGINE BIIUKJNG CONDITIONS. ENGINE sPE£|:|15|]|] ppm
`EXHAUST ens warm-up BATE ssomsuen t ens vs. sent! in
`25 3:19’-5
`
`PRESSURE—Pa
`
`f”
`
`TIMING 27° ETC
`TIMING 9° BTE
`
`RELEASED ENERGY —
`KW—HR
`
`C|.|MULl\T|VE*"_
`HEAT
`RELEJKSE
`
`BRANKANBLE-DEGREE
`
`Fig. 10 - Influence of ignition timing on variation
`0f Pressure and energy during combustion
`
`Page 11 of 18
`
`

`
`CATALYTIC SYSTEM WARM-UP
`
`1661
`
`combination with the volumetric efficiency, however, the
`largest influence on the exhaust gas temperature is exerted by
`the spark timing which brings about a large increase in the
`exhaust gas temperature.
`As mentioned above, the volumetric efficiency for the
`desired indicated output is dependent on the spark timing and
`increases from about 0.25 with spark advance to a full load
`value greater than 0.8 with spark retard (see Fig. I], bottom).
`The curves of constant volumetric efficiency have the same
`tendency as the curves of constant exhaust gas temperature so
`that the desired objective of providing the hottest possible
`exhaust gas in largest possibie quantities is achieved by the
`spark retard. This result is shown clearly by the enthalpy
`diagram. The increase in fuel flow corresponding to the
`increase in volumetric efficiency with spark retard raises the
`exhaust gas enthalpy (which is related to the enthalpy at
`"ambient temperature) to a maximum of about 27"50 kcalih at
`1500 rpm (Fig. 11) whereas it is approximately 5600 kcaljh at
`2500 rpm.
`In the enthalpy diagram only the sensible heat portion of
`the exhaust energy is illustrated. The chemical energy still
`contained in the exhaust gas, particularly when there is a
`shortage of air, is not taken into account. By the use of
`appropriate devices (that is, thermal reactor with secondary air
`injection) this energy can be used to warmup the converters in
`the startup phase.
`In Fig. 11 one can see that the spark timing has a very
`intensive influence on the composition of the exhaust gases.
`The HC emissions are lowered from 400 to less than 50 ppm
`by spark retard despite the increasing amount of charge. Down
`to the spark retard running limit only a minimum rise can be
`determined. The cause of the low I-IC values are the high
`temperatures in the exhaust gas due to the del