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400 Commonwealth Drive, Warrendale, PA 15096-0001 U.S.A. Tel: (724) 776-4841 Fax: (724) 776-5760 Web: www.sae.or

2005-01-1139

Performance and Benefits of Zero

Maintenance Air Induction Systems

Neville J. Bugli and Gregory S. GreenVisteon Corporation

Reprinted From: New SI Engine and Component Design 2005(SP-1966)

2005 SAE World CongressDetroit, MichiganApril 11-14, 2005

SAE TECHNICAL

PAPER SERIES

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Copyright 2005 SAE International

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2005-01-1139

Performance and Benefits of Zero Maintenance Air InductionSystems

Neville J. Bugli and Gregory S. GreenVisteon Corporation

Copyright 2005 SAE International

ABSTRACT

Engine air filtration technologies currently used in airinduction systems typically utilize pleated paper or felttype air filters. These air filter designs have been used

for many years in panels, cylindrical or round (pancaketype) type air cleaners. Pleated air filters are specificallydesigned to be serviceable and hence their performanceis inherently limited by vehicle under-hood packagingand manufacturing constraints. Due to these constraints,majority of air cleaner designs are not optimized forengine filtration and air flow management under thehood.Studies show that use of low performing serviceableaftermarket air filters significantly affect the performanceand durability of engine air cleaners [9]. High mileagestudies confirm that engine durability, service issues,warranty field returns and customer satisfaction was

affected by use of aftermarket filter brands.

Innovative air cleaner designs are required to maximizefiltration performance, improve flow management,extend air cleaner service life and improve enginedurability. Filtration characteristics of reticulated porousfoams were studied and evaluated as a potentialsolution. Reticulated foam media has a very openstructure, which allows it to have a relatively high dustholding capacity (DHC) and capture efficiency. Thepotential benefits of reticulated foam filters are longerlife, competitive cost and flexibility in packaging. A foamfilter model was also developed to predict performances

of multi-layer reticulated foam filters. Model predictionsfor a four layer foam filter design have been presentedand discussed.

A new Long Life Filtration System was developed forOEM (Original Equipment Manufacturer) applications(2003/2004 Ford Focus Vehicle) and requirements. Thisnew technology uses a unique multi-layered reticulatedfoam media which does not need servicing ormaintenance for the life of the vehicle [150K+ miles].This technology also provides some unique advantagesover the traditional serviceable air induction filters.

Accelerated field evaluations are also presented tosupport the new Visteon technology using Long LifeFiltration System. These studies show the viability andflexibility of multi-layer foam designs.

Keywords: Long Life Filters, Long Life Air CleanersReticulated Foams, Multi-layered Foams, non-serviceable, zero maintenance.

NOMENCLATURE

AIF = Air Induction FiltersAIS = Air Induction SystemsCARB = California Air Resource BoardDHC = Dust Holding capacityEAC = Engine Air CleanersEIS = Engine Induction SystemsISO = International Standards OrganizationLLF = Long Life FiltrationMAFS = Mass Air Flow SensorNA = North AmericaNVH = Noise Vibration and HarshnessOEM = Original Equipment ManufacturerPPI = Pores Per InchPZEV = Partial Zero Emission Vehicle

INTRODUCTION

Foam filters have been used in the aftermarket formotorcycle and high performance vehicle air intakesystems with limited success. Most foam filter designsare super-saturated with viscous oils or tackifiers toimprove their filtration performance levels. This is furtheevidenced by the oil puddle that collects in the plastic

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bag used to package these foam filters. Most of thefoam aftermarket filters exhibit high oil migration,contamination of downstream sensors, contamination ofmoving parts, poor service life and poor engineprotection. However, the successful use of OEM foamfilters for engine intake has been reported previously[1, 2, 3, 4, 5, 8].

This paper describes a new Long Life Filtration (LLF)System technology developed for OEM applications

using a unique multi-layered reticulated foam media andair cleaner design. Filtration characteristics of reticulatedporous foams were studied and evaluated. Multilayeredreticulated foam media were designed having highfiltration performance levels. The multi-layeredreticulated foam maximizes the dust holding capacityand efficiency due to its depth/deep-bed filtrationproperties. This technology also provides some uniqueadvantages over the traditional serviceable air inductionfilters. A filter model was developed to predictperformances of multi-layer reticulated foam filters. Themodel can accommodate multiple foam layers in variousthicknesses. The model also allows for the foam layers

to be dry or treated to improve performance.Comparisons of experimental data to foam predictionsshow good correlation [1].

Based on the LLF technology, an innovative ZeroMaintenance Long Life engine air cleaner system wasdeveloped for 2003 and 2004 Ford Focus Vehicle.Previous papers [1, 2] discuss details of the Ford Focuslong life air cleaner development that meets all OEMrequirements. This new system is completely sealed anddoes not require any service for 150K+ miles. This paperpresents further performance enhancements to theoriginal design [1, 2].

With the long life system, OEM's will enjoy substantiallyreduced warranty costs associated with air filter service.Consumers will no longer need to worry about usingsub-standard replacement filters and additionalinstallation problems that can damage engines [9, 10].This new technology can save consumers between $100and $300 over the life of the vehicle. Higher cost savingsmay be realized for dedicated fleets and rentalcompanies.

ENGINE AIR INDUCTION SYSTEMS

Engine air induction systems are designed to meetengine protection requirements, engine durabilityrequirements, air flow management, horse-powertargets, achieve desired torque tuning, water/snowingestion management, NVH targets, vehicle soundtuning and more recently managing evaporativeemissions. Tradeoffs in performance requirements areoften made in designing air induction systems based onOEM customer requirements [10, 11, 12, 13].

Engine Air cleaners [EAC] are designed to effectivelyremove airborne contaminants in order to protect theengine throughout its service life [12]. The enginerequires that the ingested air meet a minimum level ofcleanliness to reduce engine wear, improve engineefficiency and protect electronic sensors [12]. Howeverin actual service when aftermarket components(especially air filters) are used the OEM design integrityis generally compromised. The majority of the air filtersavailable in the aftermarket exhibit poor performance

levels [9]. Use of low performing aftermarket filters maylead to excessive engine wear and systemcontamination [6, 9, 10]. A robust engine air cleaneshould meet and exceed the following parameters.

1. Maximize the available package space2. Improve filtration performances;

a. Higher fine dust efficiency &b. Higher fine dust capacity

3. Accommodate higher engine flow rates andmedia face velocities

4. Reduce overall engine wear5. Improve engine power/torque

6. Improve MAFS performance7. Allow competitive costs8. Meet evaporative emissions over 150K miles9. Improve sealing to meet LEVII, ULEV & PZEV10. Withstand higher under-hood temperatures11. Extend filter service life12. Improve engine durability to 150K+ miles13. Reduce parts complexities14. Improve Recyclability

ENGINE AIR INDUCTION SYSTEMS AND

AFTERMARKET AIR FILTERS

OEM (original equipment manufacturers) air inductiondesigns are optimized to meet required levels ofperformances using a systems approach and synergyfor the vehicle. Invariably, when aftermarket componentsare used the design integrity and durability of the OEMsystem is compromised. Use of aftermarket air filters inOEM air cleaners presents a very challenging dilemmaHigh mileage studies conducted by Ford MotorCompany in 2000 - 2002 clearly indicated that; a)aftermarket air filters and b) mis-assembly of the aicleaner parts significantly contributed to field returns andhigher warranty issues. Their high mileage studiesyielded the following issues;

- OEM air cleaner design integrity could becompromised

- Broken and cracked air cleaners were observed- Air cleaners had severe leakage issues- Aftermarket air filters were very difficult to service- Mis-assembly of parts during service was highly

probable even when no tools were required.- Majority of the air filters were pre-maturely

serviced.- Engines exhibited stalling and starting issues.- Mass Air Flow Sensor contamination was high.

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Figure 1 shows pictures of OEM engine air cleanersfrom high mileage fleet evaluations. The air cleanersexhibited filter seal tear and filter collapse into the tray.Figure 2 shows typical aftermarket air filter for a lighttruck application. These aftermarket filters exhibited filterwarpage and loss of performance. Additional informationon performance of aftermarket filters can be found inreference [9, 10]. The filters could exhibit pleat collapse,pleat separation, torn seals and permanent compressionset on seals.

Figure 1: Typical examples of air cleaner field returnsfrom high mileage study using aftermarket filter brands.

ENGINE AIR INDUCTION SYSTEMS AND FILTER

SERVICE LIFE

Estimating service life for a particular engine size orvehicle can be complex. However, understandingservice life requirements is crucial for optimum engineprotection. Engine air cleaners should be serviced after

they have reached or surpassed an allowable restrictionrise due to contaminant loading [11]. Further, the point atwhich the engine air cleaners are serviced affects both,filtration performance and overall vehicle performance.Engine air cleaners having excessive restriction valuescan significantly degrade overall engine performance. Ithas been well demonstrated that the filtration efficiencyof the AIF improves with contaminant loading [7, 12].With an increase in efficiency, the engine wearsignificantly decreases [7]. Servicing air filters at therecommended (design intent) restriction rise or pressure

loss, allows the filter to achieve its highest efficiencythus providing maximum engine protection. Frequentlyservicing the air filter, especially within the first 30% ofits service life can significantly increase engine wear [7].

Figure 2: Typical examples of warped aftermarkefilters.

In reality, engine air cleaners are pre-maturely serviced

by the end customer. As a result the customer neveutilizes the full value of the air filter. This is due to thefact that the engine air filter never achieves its highesefficiency levels, thus reducing overall engine protectionby increasing the rate of engine wear [7, 11, 12]. Figure3 shows the efficiency of a typical engine air cleanerusing a pleated paper filter design. Data for figure 3 wasgenerated from benchmark studies on air inductionsystems. Figure 3 shows that the air filter never reachesits full efficiency (illustrated by dash line). The customeris also throwing away a perfectly good filter, whichincreases the cost of vehicle ownership.

SERVICE LIFE CRITERIA - Service life expectations folight, medium & heavy-duty vehicles are differentTypical service interval for light/medium duty vehiclesunder normal driving conditions is about 30K milesEngine performance for light and medium vehiclesgenerally requires that most EAC should be servicedonce the restriction rise has reached or exceeded abou2.5 kPa beyond initial restriction [10, 11].

Service life expectations are generally recommended fornormal driving conditions. Typically, that includes the

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97th percentile customer profile. Service lifeexpectations for severe/dusty driving conditions aresignificantly shorter compared to normal conditions [10,11].

Cumulative Gravimetric Efficiency vs. Dust Fed For a

Serviceable Filter Using Traditional Designs

98.0

98.5

99.0

99.5

100.0

0 100 200 300 400 500 600

Dust Fed, Gms

CumulativeEff.,

%u

sin

g

ISOF

ineTestDust

Design Intent

Service Interval

Figure 3: Efficiency performance of a typical pleatedengine air filter challenged with standard ISO fine testdust. The dotted line indicates the performancebenefits not realized by the OEM customer.

FACTORS AFFECTING SERVICE LIFE Service lifeprimarily depends on the application and end use.Factors affecting service life can be complex andmultivariate in nature. Some key factors are listed below;

- Air cleaner housing design

-Inlet (dirty) tube location

- Outlet (clean) tube location- Air Filter design- Filter media type- Filter media area- Filter dust holding capacity- Filter dust loading characteristics- Driving conditions- Type of contaminant- Contaminant Shape/Size/Concentration- Environmental conditions- Customer awareness- Cost of ownership

Various studies have been performed to predict orestimate Air Cleaner Service Life with limited success[6, 10, 11, 12]. Generally lab or bench studies areconducted to measure the performance (DHC,gravimetric efficiency, restriction, fractional efficiencyetc.) of the air filter. These studies are performed usingstandard test procedures and standard test dust,providing limited information regarding filter service life.

Analysis of extensive Real World field evaluationsindicated that using ISO Fine Test dust is most

representative of the typical field environmen[10, 11,12]. Using ISO Coarse test dust yield higher duscapacities, but have very little correlation to real worldenvironment. Table 1 below shows the summary of theextensive field evaluations performed on variouscustomer fleets and on proving grounds.

Vehicle

ContaminantLoading

g/1000 miles

ExpectedMin. Dust

Capacity**at 30K miles

service, g

ExpectedMin. Dust

Capacity**at 150K mile

Service, gSmall /Medium

PassengerCars & SUVs

2 60 300

Large/FullSize

PassengerCars, SUVs,Minivans &Lt. Trucks

3.5 105 525

Medium/Large Trucks 5 150 750

** Dust capacity expectations based on ISO FineTest Dust

Table 1: Estimated Minimum ISO Fine Dust CapacityRequired for Vehicle Segments. Data derived fromextensive field studies [10, 11, 12].

ZERO MAINTENANCE LONG LIFE ENGINE AIR

INDUCTION SYSTEM FOR ENGINE INTAKE

Engine air induction systems (AIS) typically use paper orfelt type air filters [10, 11,12]. The filtrationcharacteristics for these media are well understood andmodeled. However the model applications are fairlylimited. These designs have limitations as discussed inprevious sections above. Due to these constraintsmajority of the air cleaner designs frequently do noprovide optimal filtration and flow management underhood. However, the current OEM air cleaners aredesigned and suited for serviceability.

OEM automakers are constantly striving to providemore product value to the end customer. OEMmanufacturers are constantly improving their productsand systems to reduce both development time &manufacturing process time, and also warranty andmaintenance costs. The zero maintenance Long LifeFiltration (LLF) System makes it possible for the vehiclesto operate using the same air cleaner for at least 150Kmiles or more without requiring any maintenance oservice, under normal driving conditions.

Use of porous foam filters for engine intake and relatedair filter applications have been reported previously

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[1, 2, 3, 4, 5, 6]. For developing Visteons zeromaintenance Long Life Filtration System, reticulated(open cell) foam structures were studied ranging from 20ppi (pores per inch) up to 110 ppi (pores per inch). Bydesigning multi-layered reticulated foams using theappropriate pore sizes, the usage of viscous treatments(oils) can be significantly reduced.

The reduction of viscous treatment usage was one of thekey goals of the development team. Experience and

analysis of field failures have demonstrated that themigration of viscous treatments from a filter element canlead to contamination and subsequent failures of theMass Air Flow Sensor, and other critical engine sensors.The use of multiple layers in the filter allowed thedevelopment of a control for migration of the viscoustreatments out of the filter element. New control methodsfor applying viscous treatments were utilized in theVisteon Long Life Filtration system. Specific amounts ofoils are added to the foam, and additional processingwas utilized to distribute the oils into the center of thefoam matrix. The multi-layer construction allows thearrangement of the layers to provide a barrier to oil

migration into the air stream.

An additional benefit afforded from the use of multi-layerfoam construction is that reticulated foam can be coatedwith activated carbon. The resulting structure functionsas both a collector of dust particles and an adsorber ofhydrocarbon vapors. A filter that contains such anadsorbing layer, and designed with DHC to exceed 150Kmiles, provides an OEM with an integrated solution to airfiltration and under hood evaporative emission control.

The new sealed zero maintenance LLF air cleanerdesign can provide an attractive package as a stand-

alone or a complementary system to support a full PZEVsolution. PZEV development as it relates to AIS isdiscussed in a separate technical paper [13]. The nextgeneration of engine air induction systems will have tosupport and meet United States Tier 2, California LEV-II(low emission vehicle) and PZEV vehicle emissionrequirements. The California Air Resources Board(CARB) is mandating the LEVII and PZEV requirementsfor 15 years/150K miles. It has already been establishedthat hydrocarbon vapors flowing and/or diffusing outfrom the inlet manifold and engine will have to bereduced or removed to meet the new LEV-II and PZEVrequirements. For PZEV designated vehicles, OEMautomakers have determined that the use of aftermarketcomponents may seriously compromise the design andfunctional integrity of the air cleaner system.

MULTILAYERED FOAM MEDIA - Open cellpolyurethane foams are engineered in various poresizes ranging from 20 to 100 ppi (pores per inch). Thepore sizes are defined based on a pressure drop method(MIL-PRF-87260A {UASF} 1998). Polyurethane foamshave a very unique 12-sided three-dimensional structurealso known as a Pentagonal Dodecahedron structure.Each of the 12 cell sides is pentagon in shape [1,3,4,5].

The pentagon is formed by struts or strands. A wholematrix of these cells make up the foam giving it a veryhigh permeability and surface area, ideal for depth ordeep bed filter design. Porous foam media have beenused in various filtration applications to remove airborneparticles for low efficiency filtration applications. Porousfoams when used in a multi-layered configuration caneffectively be used for medium to high efficiency filtrationapplications [1, 2, 3]. All known filtration mechanisms arepresent within the foam structure to collect particles. The

reticulated foam filter media provides the followingbenefits:

Reticulated 'open cell' foam is about 96%-98%porous.

High surface area for contaminant collection. Foams can be accommodated in multiple shapes

and sizes. Foams are durable materials resistant to wate

and snow and solvents. Available in multiple pore sizes. Fairly uniform pore size distribution. Selective layers can be treated with viscous oils

to improve filtration performances. High dust capacities and efficiencies are

possible. Cost effective

For reticulated foams the pore size and strand (fiber)diameter are important parameters to control filtrationperformance levels. Figure 4 shows an example of aclean reticulated and dust loaded ( light and heavyfoam. The dust loading clearly shows the dendriteformation of the dust around the strands within the pore.

FOAM FILTER MODEL - A semi-empirical model hasbeen developed to predict pressure drop, collection

efficiency, dust loading behavior of foam filters andestimate service life. Model can be applied to any Porecount between 20 and 110 pores per inch using multiplelayers. The model is suited for reticulated foam having abasis weight in the range of 24 32 kg/m3 (1.5 2.0lb/ft3). The pressure drop model applies to facevelocities in the range of 75 to 300 m/min. Overalaccuracy of model predictions is about 20% focollection efficiencies, pressure drop and dust holdingcapacities. The model predictions are based on uniformflow conditions.

The model can accommodate up to 12 layers of foam

dry or selectively treated to capture dust. The modepredicts pressure drop, dust capacity, initial and overalgravimetric efficiencies at selectable pressure drop risesof up to 5 kPa beyond initial restriction.

In addition, the model also predicts performance oindividual layers in terms of restriction rise, dust loadingand cumulative gravimetric efficiency. The performancepredictions of individual layers are critical in designingthe multi-layer foam filter. The model also predicts thefractional size efficiency of the multi-layer foam. Modeinput/output parameters are briefly listed below

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Figure 4: Example of a clean and dust loaded foamfilter.

Input Parametersii Number of layersii Thickness of each layerii Dry or Treatedii Face velocity through mediaii ISO coarse or fine test dustii Terminal pressure drop riseii Assumes uniform flow distribution

Output Parametersoo Initial clean pressure dropoo Initial mass efficiencyoo Differential dust distribution on each layeroo Cumulative dust distribution on each layeroo Total Dust mass loadingoo Fractional size efficiencyoo Service life prediction

The model was used to predict the performance of ahigh capacity 4 layer zero maintenance long life foamfilter. The 4 layer foam design would meet or exceedperformance levels typical of current filtrationtechnologies used on engine air cleaners [2, 9, 10, 12].The foam media was about 63.5 mm in thickness with afootprint of about 600mm2. The prediction curves thatfollow illustrate the modeling capabilities of foam filters.Figure 5 shows the predicted pressure drop vs. facevelocity of the 4 layer foam. The pressure dropincreases can be approximated by a power function.

When the face velocity is doubled the pressure dropincreases by about a factor of three. Figure 6 shows thepredicted dust holding capacity vs. face velocity. In therange of 100 to 250 m/min., the dust DHC can belinearly approximated. For example the dust holdingcapacity dropped by about 30% when face velocity wasdoubled.

Figure 7 shows the predicted initial and overall efficiencyof the 4 layer media. Figure 7 also shows the targetminimum efficiencies required when using ISO fine test

dust under normal driving conditions. Efficiency curvesshow that the design optimal face velocity for the 4 layefoam design is in the range of 100 to 200 m/min..

Example of Multilayer (4-layer) LLF Model Predictions

Face Velocity vs. Pressure drop

y = 0.0003x1.6003

0.0

0.2

0.4

0.6

0.8

1.01.2

1.4

1.6

1.8

2.0

0 50 100 150 200 250 300

Face Velocity, m/min.

pressuredrop,

kPa

Figure 5: Pressure drop vs. Face Velocity prediction fora 4 layer long life filter.

Example of Multilayer (4-layer) LLF Model Predic tions

Face Velocity vs. Dust Capacity

y = -1.5795x + 833.8

300

350

400

450

500

550

600

650

700

0 100 200 300


dustcapacity,g

w/ISO

Finetestdust

Figure 6: Predicted Dust Holding Capacity vs. FaceVelocity for a 4 layer long life filter.


Face Velocity vs. Gravimetric Efficiency

97.0

97.5

98.0

98.5

99.0

99.5

100.0

0 50 100 150 200 250 300


dus

tcapa

city,

gw

/ISO

Finet

es

tdus

t

targets

overall

efficiencyinitial

efficiency

Figure 7: Predicted Gravimetric Efficiency vs. FaceVelocity for a 4layer long life filter.

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As expected the efficiency increases with increasingface velocity, as the dominant particle capturemechanism is by interception and inertia [8]. Theefficiency drop off at higher face velocities may beattributed to particle bounce and re-entrainment.Multilayer foam filters can be designed for a range ofvelocities. Depending on the number, type and size ofmultilayer foam filters the optimal face velocity rangemay be different.Figure 8 shows the estimated service life of the 4 layerfoam for a large passenger car application. The servicelife varies almost linearly with face velocity. Based onthe optimal design face velocity of 100 200 m/min., theservice life can range from 148K to 190K miles.


Face Velocity vs. Service Life

y = -431.77x + 234677

100000.0

125000.0

150000.0

175000.0

200000.0

0 50 100 150 200 250 300


ServiceLife,miles

Figure 8: Estimated service life for a 4 layer foamdesigned large passenger car.

Figures 9 and 10 show the effect of increasing thicknessof multilayer layer foam filter. The foam filter wasdesigned to operate at a face velocity of 150 m/min. Foreach increasing thickness the foam layers weredesigned to maintain the same initial and overallremoval efficiencies. The end effect was to offer thesame engine protection with increasing dust capacitiesand service life. Figure 9 shows the effect of increasingthickness on restriction rise. The pressure drop can beapproximated by a power function. However in the rangeof interest, the pressure drop increase was almost linear

with increasing thickness.

Figure 10 shows the effect of thickness on dust holdingcapacity. The dust capacity can also be closelyrepresented by a liner function. It is interesting to notethat doubling the thickness only increased the restrictionrise by about 20%. However doubling the thicknessincreased the dust capacity by about 90% (almostdouble).


Media Depth vs. Pressure drop

y = 0.3232x0.2234

0.5

0.6

0.7

0.8

0.9

1

0 50 100 150

Media Depth, mm

pressuredrop,

kPa

Initial Gravimetric Ef f.= 99.11%

Overall Gravimetric Ef f. = 99.84%

Face Vel = 150 m/min

Figure 9: Predicted Restriction Rise vs. Media Depth fora 4 layer long life filter.


Media Depth vs. Dust Capacity

y = 9.8175x

300

400

500

600

700

800

900

1000

1100

1200

0 50 100 150

Media Depth, mm

DustCapacity,gw/ISO

FinetestDust

Initial Gravimetric Eff.= 99.11%

Overall Gravimetric Eff. = 99.84%

Face Vel = 150 m/min

Figure 10: Predicted Dust Capacity vs. Media Depth fora 4 layer long life filter.

LONG LIFE FILTER REAL WORLD FIELD

STUDIES

A production prototype air cleaner was developed for alarge passenger car application equipped with a 4.6L 2-

valve engine at a rated flow of 9.91m3/min. Figure 11shows the location of the Long Life filtration System infleet vehicles. The Long Life filtration System waspackaged outside the engine compartment and behindthe front bumper below the driver side headlight. Figure12 shows a cut-away view of the air cleaner showing thefoam multilayered filters.

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Figure 11: Long Life AIS used in Fleet Study. Thesystem was packaged outside the engine compartment.

Figure 12: Cut Away View of the Long Life Air Cleanerused in Fleet Study.

Extensive field evaluations were performed on the aboveLong Life filtration System using multi-layer foams over a2- 3 year period at four different locations in North

America (NA). Field evaluations were performed at; 1)New York City, 2) Orlando, 3) Las Vegas and 4) Phoenix- Maricopa County [1,2]. Additional information can befound on the fleet studies in ref. 1 and 2.

All fleet vehicles operated on a single long life filtrationsystem for 2 to 3 years without any customer complaintsor engine performance degradation. These systems didnot require any maintenance or service actions duringthe entire study period. Customer satisfaction withengine and filter performance was high [1, 2].

Figure 13 shows the mileage accumulated and therestriction rise for all fleet vehicles (38 vehicles). Therestriction rise was measured on a bench test beforeand after the fleet tests were concluded (2 to 3years).The restriction rise does not show a continuousincreasing trend with mileage. This was expected as thevehicles were operating in four different environmentsand driving conditions. The dash line shows therestriction rise trend. On average the vehiclesaccumulated about 109K miles with a restriction rise of0.94kPa.

Total Mileage and Restriction Rise For All Vehicles

0

50000

100000

150000

200000

250000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 1516 17 18 19 20 21 22 2324 25 26 27 28 29 3031 32 33 34 35 36 37 38

Vehicles

Distan

ce,

miles

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

Miles Res tric tion Rise

Figure 13: Miles accumulated and restriction rise onfleet study.

The data for contaminant loading and restriction rise wasalso plotted in Figure 14. There is an increasing trend orestriction rise with contaminant loading. On average wecan expect about 500g of contaminant collected at a2.5kPa restriction rise.

Dust spot efficiency was also measured on random LLFair cleaners returned from the field. The spot efficiency ismeasured after feeding 20g of ISO fine test dust on thefiltration stand using maximum rated flow conditionsFigures 15, 16 and 17 all show increasing efficiencylevels with contaminant loading, miles accumulated and

restriction rise. These increasing trends are desirable asit demonstrates the reliability of the LLF filter aftecontaminant loading and with time. On average the dusspot efficiency increased from about 98.85% to 99.3%with contaminant loading.

Overall Contaminant Loading vs. Restriction Rise

All Fleet Data

0.0

1.0

2.0

3.04.0

5.0

6.0

7.0

8.0

100 1000Contaminant Loading, g

Res

triction

Rise,

kPa

Figure 14: Contaminant loading and restriction rise forfleet study.

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Contaminant Loading vs. Measured Dust Spot

Efficiency - All Fleet Data

98.098.298.498.698.899.099.299.499.699.8

100.0

0 100 200 300 400 500 600

contaminant loading, g

Du

st(gravimetric)

SpotEfficiency,

%

Figure 15: Contaminant loading vs. dust spot efficiency.

Mileage Accumulated vs. Measured Dust Spot


98.2

98.4

98.6

98.8

99.0

99.2

99.4

99.6

99.8

100.0

0 50000 100000 150000 200000 250000 300000

Vehicle Miles

Dust(gravimetric)Spo

t

Efficiency,

%

Figure 16: Vehicle miles accumulated vs. Dust spotefficiency

Figure 18 shows the overall normalized contaminantloading based on data from all fleet vehicles. Onaverage we can expect about 2.1g/1000 miles. Basedon confidence limits we can expect about 3.5g/1000miles of contaminant loading at 99% confidence. Hence,at a service life of 150K miles we can expect about 525gof total contaminant to be ingested.

Table 2 below compares the lab bench measurementsto model predictions for the Long Life Filtration systemsused in the taxicab fleet study. The dust capacitymeasurements based on model predictions were within

20%. The efficiency predictions were within 0.5%.Based on these measurements the LLF for the taxicabfleet may not require any service for 95K miles.

Restriction Rise vs. Measured Dust Spot


98.2

98.4

98.6

98.8

99.0

99.2

99.4

99.6

99.8

100.0

0 1 2 3 4

Restriction rise. kPa

Dust(gravimetric)Spot

E

fficiency,

%

Figure 17: Restriction rise vs. Dust spot efficiency

Overall Contaminant Loading Data Including

All Fleet Vehicles

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

avg 95% confidence 99% confidence

contaminantcollected,g/1000mile

Figure 18: Normalized Contaminant loading.

Long life filtrationsystem

Experimental Data

Long lifefiltration system

ModelPredictions

Dust Capacity, g 333g 287 g

Initial Gravimetric

Efficiency, %

98.41% 98.47%

OverallGravimetric

Efficiency, %98.83% 99.35%

Flow rate= 8.0 m3/min. constant

Test Dust = ISO fine

Table 2: Experimental data compared to modelpredictions for Long life filtration used in Taxicab FleetStudy.

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BENEFITS OF ZERO MAINTENANCE LONG LIFE AIRINDUCTION SYSTEMS - The zero maintenance LLF aircleaner design offers some unique and significantadvantages to OEM automakers and end usagecustomers. Some of the performance benefits havebeen discussed above. Additional key design benefitsinclude the following;

1. Increases air filter service intervals over 150Kmiles.

2. Improves robustness and durability of airinduction systems.

3. Provides OEMs and end customers a completesolution hassle free design.

4. Allows a variety of geometric shapes to bepackaged.

5. Allows increased packaging flexibility.6. Reduces vehicle lifetime service cost.7. Reduces the impact of serviceable filters

occupying landfills.8. Minimizes the possibility of using substandard

aftermarket filters during the warranty period.9. Allows manufacturing complex geometries

compared to traditional paper and felt typefilters.

10. Allows ease of filter design tuning to localmarket requirements.

11. Enables incorporation of evaporative emissioncontrols to meet PZEV and LEVII vehiclerequirements for the sealed air cleaner design

12. Allows use of a proprietary filtration to quicklydesign LLF system performances.

A PRODUCTION ZERO MAINTENANCE LONG

LIFE ENGINE AIR INDUCTION SYSTEM FOR

SMALL PASSENGER CAR ENGINE

A sealed production Long Life Filtration System wasdesigned and developed for a small passenger carapplication [2003/2004 Ford Focus]. Additionalinformation on the Long Life Filtration System designand performance can be found in Bugli N et. al [1,2]. TheLong Life Filtration System requires zero maintenanceand service for 150K miles under normal drivingconditions. The Long Life Filtration System is packagedoutside the engine compartment. Figure 19 shows theLLF design as installed in the vehicle. The air cleaner iscompletely sealed and packaged outside the engine

compartment behind the front bumper on the driver side.The inlet tube was packaged in the fender area forimproved water protection and lower restriction asshown in Figure 19. The outlet tube uses a slot-in MAFSdesign for improved performance. The large plenumdownstream of the air cleaner includes a soundattenuating resonator and a hydrocarbon emissionsarrestor for vehicles requiring PZEV compliance [1, 13].

The new Visteon Long Life Filtration System uses aunique multi-layered reticulated foam media andconstruction for OEM applications to trap and remove

contaminants. The use of multi-layer reticulated foamaccommodates complex geometries, which further aidsthe LLF in packaging flexibility, freeing up valuable reaestate under the hood and around the engine. Theperformance of the LLF can be tuned to meet normadriving conditions using proprietary CAE models.

Figure 20 shows the complete Long Life Air Inductionsystem removed from the vehicle. This system wasinitially developed for the 2003 Ford Focus PZEV

vehicles. For the 2004 MY all Ford Focus have adaptedthis system across the board.

Figure 19: Zero Maintenance Sealed Long Life AirCleaner System for 2003/4 Ford Focus.The Long LifeFiltration System is covered by one or more VisteonPatents. Additional patents are currently in progress.

Figure 20: Production Long Life Air Induction Systemshown from inlet tube to throttle body inlet.

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Figure 21 shows a cross-section of the sealed LLFdesign. The cross-section shows the multi-layeredreticulated foam used for achieving higher filtrationperformance. Selective layers of the reticulated foam aretreated with commercially available chemicals, toenhance the contaminant trapping efficiency of the LLF.The foam layers are also trapped and held rigidlybetween two plastic screens. The plastic screens aredesigned to be part of the air cleaner cover and trayassembly and are necessary to achieve the desired

filtration performance levels.

Figure 21: Details of Multilayer Foam For ZeroMaintenance Sealed Long Life Air Cleaner System

ZERO MAINTENANCE LONG LIFE FOAM FILTERPERFORMANCE Long Life air cleaners wereextensively tested in the lab and in real world fieldenvironments. ISO fine test dust was used for allevaluations to more closely represent actual field loading[11]. The production LLF air cleaner design meets orexceeds known customer OEM engineeringspecifications as applied to conventional air cleaners.More details on air filter testing and specifications arecovered in reference [14].

Figure 22 compares the average dust capacitymeasured on traditional technologies and a clean Long

Life filter using ISO fine test dust [10]. The target dustcapacity was set at 300g using ISO fine test dust [2].The target capacity was calculated based on fieldevaluations and specific engine size for this application[2, 10, 11]. On average the LLF holds about 500g of ISOfine dust at a 2.5 kPa restriction rise. This targetcapacity represents a service interval of 150K miles forthe Ford Focus application based on normal drivingconditions [Table 1]. Compared to traditionaltechnologies the Long Life filter achieves about 2.5 to 5times higher dust capacity.

Average Dust Capacity Measured Using ISO Fine Test Dust @

2.5 kPa Restriction Rise

0

100

200

300

400

500

600

700

800

900

1000

1100

Dry Paper

Technology

Treated

Paper

Technology

Synthetic Felt

Technology

2003/4 Ford

Focus Long

Life

Technology

Long Life

Technology

Capability

D

ustCapacity,

Gms

Target capacity for Ford Focus = 300 g

Figure 22: Dust Holding Capacity Performance of LongLife Technology compared to Traditional designs.

Figure 23 compares the average initial gravimetric

efficiencies measured on traditional technologies to aclean LLF using ISO fine test dust [10]. The initiagravimetric efficiency target was set at 98% min. usingISO fine test dust. The target efficiency was calculatedbased on OEM benchmark data covering over 150vehicle types [10]. On average the LLF achieved aninitial efficiency of 99.5%. Compared to traditionatechnologies the Long Life filter initially allows about 4times lower dust penetration to the engine. This can besignificant for engine wear, protection and durability [7].

Average Initial Gravimetric Efficiency Measured @ 20 Gms of

ISO Fine Test Dust

96.0

96.5

97.0

97.5

98.0

98.5

99.0

99.5

100.0

Dry Paper

Technology

Treated

Paper

Technology

Synthetic Felt

Technology

2003/4 Ford

Focus Long

Life

Technology

Long Life

Technology

Capability

InitialGravmetricEff.,

%Target capacity for Ford Focus

= 98% minimum

Figure 23: Initial Efficiency Performance of Long LifeTechnology compared to Traditional designs.

Similarly Figure 24 compares the average overalgravimetric efficiencies measured on traditionatechnologies and a clean LLF using ISO fine test dust[10]. The overall gravimetric efficiencies were measuredat a 2.5kPa restriction rise. The overall gravimetric

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efficiency target was set at 98.5% min. using ISO finetest dust. The target efficiency was calculated based onOEM benchmark data covering over 150 vehicle types[10]. On average the LLF achieved a high overallefficiency of 99.5. Compared to traditional technologiesthe Long Life filter allows about 1.5 to 3 times lower dustpenetration to the engine. Again, this can be significantfor engine wear, protection and durability [7].

Average Overall Gravimetric Efficiency Measured @ 2.5 kPa

Terminal Restriction Rise Using ISO Fine Test Dust

98.0

98.5

99.0

99.5

100.0

Dry Paper

Technology

Treated

Paper

Technology

Synthetic Felt

Technology

2003/4 Ford

Focus Long

Life

Technology

Long Life

Technology

Capability

OverallGravimetricEff.,

%Target capacity for Ford Focus

= 98.5% minimum

Figure 24: Overall Efficiency Performance of Long LifeTechnology compared to Traditional designs.

Figure 25 shows one of the primary advantages of usingthe Long Life Filter Technology. Figure 25 compares thehigh efficiency level of the Long Life filter to traditionalserviceable filters [Figure 3]. Clearly, the Long Life

technology offers better engine protection throughout thevehicle life.

Cumulative Gravimetric Efficiency vs. Dust Fed comparing

Serviceable Filters and Long Life Technology

98.0

98.5

99.0

99.5

100.0

0 100 200 300 400 500 600

Dust Fed, Gms

CumulativeEff.,

%u

sing

ISO

FineTestDust

Design Intent

Service Interval

Ford Focus Long

Life Technology

Figure 25: Efficiency increase of Long Life Filtercompared to traditional pleated filter. The dashedline indicates the performance benefits not realizedby the OEM customer.

Figure 26 shows the restriction rise of the Ford FocusLong Life Filter with dust loading. The restriction rise ratewas very linear with dust loading and is predictable. Thistrend is significantly different when compared totraditional filter designs where a prominent change overpoint is present when dust cake formation takes overThis was expected as the foam filter behaves like adepth media.

Restriction Rise vs. Dust Fed

Ford Focus Long Life Filter

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

0 100 200 300 400 500 600 700 800

Dust Fed, g

RestrictionRise,

kPa

Figure 26: Pressure drop rise vs. dust loading for theFord Focus Long Life Filter.

The measured performance of the Ford Focus Long LifeFilter was also compared to model predictions. Table 3shows the comparisons. The model predictions comparefairly well. The capacity predictions are within 20%. The

efficiency predictions were within 0.5%. The restrictionpredictions were within 25%.

LLFExperimental

Data (average)Ford Focus AIS

LLF ModelPredictions

Ford Focus AIS

Dust Capacity, g 499g 609g 130gInitial Gravimetric

Efficiency, %99.52% 98.9%

Overall Gravimetric

Efficiency, %99.48% 99.51%

Filter Restriction,kPa

1.13.315 0.94 0.125

Flow rate= 6.4 m3/min. variable

Test Dust = ISO fine

Table 3: Experimental Long Life filter performancecompared to model simulations

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SUMMARY

Field evaluations and laboratory analysis successfullydemonstrates the viability and flexibility of Long LifeFiltration System designs.

Model predictions correlate with experimental data forfilter performance levels. Capacity and Restrictionpredictions using the model are within 20% and theefficiency predictions are within 0.5%.

The multi-layer foam technology provides superiorfiltration, and therefore engine protection, as comparedto standard OEM filters designed for regularreplacement. The multi-layer foam filter technology alsoprovides improved performance when compared to filtermedia that are serviced by cleaning at regular intervals.The greatest areas of improvement are in filter efficiencyand the elimination of filter oil migration.

The Long Life Filtration System challenges the customerand after-market perceptions that the air filter needs tobe replaced every 5K to 30K miles, especially under

normal driving conditions. The LLF design minimizes thepossibility of using substandard aftermarket filters duringthe warranty period.

Zero Maintenance Long Life Filters can be veryeffectively designed to meet and exceed customerrequirements for the life of the vehicle (150K miles)

Long Life Filtration System designs offer the OEMcustomer some very unique advantages and value overthe life of the vehicle.

a. Improved system reliability and robustness over the

life of the vehicleb. Reduced operating, design and warranty costs.

c. Improved packaging benefits.

d. Improved tuning filter design to local marketrequirements using the proprietary filtration model.

e. Reduced landfill waste. The VLLF is constructedfrom 100% polymers, easy to recycle. There are noused filters to be disposed to landfills.

f. 'Sealed for life' to provide the required resistance toconsumer tampering with emission controls in the

AIS.

g. Added hydrocarbon trapping layer to achievereduced evaporative emissions for LEV II Tier2compliance, or to achieve 'zero' evaporativeemissions for PZEV certification.

h. Low cost of ownership compared to more traditionalair cleaner designs, saving consumers $100 to$300 over the life of the vehicle (Higher costsavings may be realized for dedicated fleets andrental companies).

CONCLUSIONS

OEMs and vehicle owners can realize numerousbenefits from the elimination of maintenance to thevehicle, as has been demonstrated with 100,000 milespark plugs, long life coolants, and electronic ignitionsystems. The Long Life Filtration technology developedby Visteon Corporation provides a method for minimizingthe requirements to replace or clean engine air filtersZero maintenance filtration for engine air cleaners have

been modeled, tested and validated in vehicle fleets fordurability and robustness. The multilayer foam filtrationtechnology is a cost effective method to eliminate engineair filter maintenance while improving engine durabilityreducing evaporative emissions, and reducing overalmaterial usage.

REFERENCES

1. Bugli N. J and Green G. S, " Air Induction SystemsUsing Long Life Reticulated foam Media", TechnicaPaper Presented at the World Filtration Congressand Exposition, New Orleans, , Louisiana, April 19 -

22, 2004.

2. Bugli N. J and Dixon C. J, " Long Life Engine AirCleaner Technology For Automotive PassengerCars, SUVs and Light Trucks", Technical PaperPresented at the American Filtration andSeparations Society, 16th Annual Conference andExposition, Reno, Nevada, June 17-20, 2003.

3. Pizzirusso J. F., "The Unique Properties oPolyurethane foam for small engine filters", SAEtechnical paper 951811.

4. Curti C. M," Reticulated Polyurethane Foam"

Technical paper, Automotive EngineeringInternational Publication, Vol. 109 No. 6, June 2001pages 88 92.

5. Rucker J.," reticulated Polyurethane Foam For theFiltration Industry", Technical Paper presented atINDA Filtration 2001 Conference.

6. Nouis R., (1993), " Predicting the Ninety-FifthPercentile Dust Environment for Passenger Vehiclesin the Continental United States," SAE technicapaper 930018, presented at the SAE InternationaCongress and Exposition, Detroit, March 1-5, 1993.

7. Barris M., (1995), "Total Filtration: The Influence of

Filter Selection on Engine Wear, Emissions, andPerformance," SAE technical paper 952557, Fuels &Lubricants meeting and exposition, Toronto, Octobe16-19, 1995.

8. Poon W. S., Liu B. Y. H and Bugli N. J, (1997),"Fractional Efficiency and Particle Mass LoadingCharacteristics of Engine Air Filters", SAE technicapaper 970673, also in SAE special publication SP-1252 pp. 103 - 112, presented at the SAEInternational Congress and Exposition, Detroit, Feb.-Mar 1997.

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9. Bugli N. J and Leffel J. (2001), "Engine Air InductionFiltration Systems- Design challenges for the NextGeneration", Advances in Filtration and SeparationTechnology, Volume 15, American Filtration andSeparations Society Annual Conference, Tampa,Florida, 2001.

10. Bugli N. J, (2001), "Automotive Engine Air Cleaners Performance Trends", SAE technical paper, 2001-

01-1356, presented at the SAE InternationalCongress and Exposition, Detroit, March 5 8, 2001.

11. Bugli N. J, (1998), " Service Life Requirements ForEngine Air Induction Filters", Advances in Filtrationand Separation Technology, American Filtration andSeparations Society, 1998 AFS annual conference,Vol. 12, pp. 38 - 49.

12. Bugli N. J, (1997), " Filter PerformanceRequirements for Engine Air Induction Systems ",SAE technical paper 970556, also in SAE specialpublication SP-1252 pp. 55-69, presented at theSAE International Congress and Exposition, Detroit,

Feb.-Mar 1997.

13. Leffel J. and Green G. S., Development ofEvaporative Emissions Filter for Automotive

Applications, Technical Paper Presented at theAmerican Filtration and Separations Society, 16thAnnual Conference and Exposition, Reno, Nevada,June 17-20, 2003.

14. Bugli N. J, Puckett R., and Lanier V., FiltrationChallenges and Conical Filter Development forEngine Air Induction Systems, SAE technical paper950941, presented at the SAE InternationalCongress and Exposition, Detroit, February 27 -

March 2, 1995.

ACKNOWLEDGMENTS

The authors would like to sincerely thank Mr. BrianCondron, Mr. Michael Adams, Ms. Celine Jee Dixon, Mr.Ryan Grimes, Mr. Jeffrey Leffel, Mr. Scott Flora, MsGrace Alent and Mr. Scott Dobert of Visteon Corporationfor their help and support in developing the zeromaintenance Long Life Air Cleaner.

CONTACT

Neville BugliTechnical FellowVisteon corporation734-710-4751734-736-5600 fax

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