Why Electronic FanWhy Electronic FanClutchesClutches

Have you ever heard?

Would you convert my truck to an electric fan and take off my fanclutch? The cost of gas is killing me!

Wow! That electric clutch is real expensive… Can’t you just replaceit with a regular clutch?

I just put a dual fan set up on my truck, yet it seems to overheat intraffic. They are rated around 5400 CFM that should be enough, canyou help me?

I just added an electric fan on my Excursion for towing my boat, andit seems like the A/C just isn’t what it used to be, can you help me?

Let’s Review a few essential facts about cooling…

Comprehensive InspectionComprehensive Inspection

Could these products introduce a potential reductionin cooling?

Sometimes we are pressedfor time to diagnose the rootcause of a cooling problem,and miss the customerintroduced modifications orchange in driving habits!

Which Affords Greater Air Flow?

Chassis Dynamics

Can an altered chassis impact Under HoodCan an altered chassis impact Under HoodAirflow?Airflow?

Now let’s look at a resurging air flowgenerator

When the system is cold, the working fluid (silicone)in the clutch remains in the reservoir…

Silicone

Commonalities With EVFC?

HOT AIR

In a Thermostatic clutch, hot air, blowing across the radiator hits the thermal springcausing it to turn the valve pin connected to the valve gate…

As the valve gateopens, centrifugal forcepushes silicone into theworking area of theclutch causing It toengage

The thermal springwill cause the valvegate to open fully orpartially dependingon the heat loadthereby causing thefan clutch to engagefully or partially

HOW IT WORKS

HOW IT WORKS

Centrifugal force and a scoop on the outside diameter of the impellerpumps the fluid from the working area of the clutch through a returnchannel to the reservoir…

HOT AIR

HOW IT WORKS

Once the fan has cooled the radiator enough, cooler air hits thethermal spring causing it to retract thereby closing the valve gate…

COOLER AIR

With the valvegate closed,silicone ispumped intothe reservoirwhere itremains untilheat again hitsthe thermalspring actuatingthe valve gate

If the thermal spring is not working correctly?

Clutch Over-Run & CAFE

1 3 5 10 15 2030 60

Standard DutyHeavy Duty

Severe Duty0.0

20.0

40.0

60.0

80.0

100.0

120.0

140.0

160.0

TIME (MINS / HR) THAT FAN CLUTCH OPERATES BEYOND NEED

TYPE OF FAN CLUTCH

ANNUAL FUEL COSTS FOR MAL-FUNCTIONING FAN CLUTCHES

Standard Duty

Heavy Duty

Severe Duty

Assumptions:1. Engine speed of 2000 RPM & Water Pump @ 2500 RPM, Vehicle speed= 50 MPH (80 Km/Hr)2. Average Fuel Consumption : 20 MPG (8.5 l/kM)3. Annual Mileage: 20,000 miles (32,180 kM)4. Cost of Fuel: $2.00/gal (0.528 US$/l)

Why Electronic Viscous Fan Clutches?

CAFE

EVFC Operation (GM)

Let’s Breakdown the Components!

Actuator is removed fromthis GM unit…

Exposed is the connectingnut and solenoid core

Connecting Nut

Solenoid Core

Actuator & Fan Speed Sensor

The GM unit contains theThe GM unit contains thefollowing:following:

Valve Actuator

Sensor Circuit

Trigger Wheel

Hall Effect Switch

Trigger Wheel

Sensor Circuit

LetLet’’s Take a Closer Looks Take a Closer Look……

Actuator & Solenoid Core

ActuatorActuatorCoilCoil

Mounting NutMounting Nut

Solenoid CoreSolenoid CoreBearingBearing

Board With Hall SensorBoard With Hall Sensor

Linear Controlled

How Does it Modify Clutch Action?

Pulse width signalsupplies a Ground Paththrough Pin # 2.

This completes thecircuit and the coilexcites the oil controlvalve.

This actuation allowseither more or lessviscous fluid to flowinto the plate area.

Coil

GM Strategy

InputInput AnalysisAnalysis CommandCommand

•Fan Speed

•Water Temp

•TransmissionTemp

•AC Ref.Pressure

•ACT Temp

•Ambient Temp

•Vehicle Speed

100% Duty CycleIf…

•Coolant exceeds264 degrees.

•Trans Oilexceeds: 300degrees.

•AC pressuresreach 240 psi.

The fan iscommanded toless than 100%under all otherconditions.

Actuation ofthe Solenoid

Valve!

2 Hz Change

Ford Clutches

FrontTether

Rear Tether

Chrysler Clutches

L6 Cummins-04-03 5.9L&6.7L 10-04

Ford-Chrysler Strategy

InputInput AnalysisAnalysis CommandCommand

•Fan Speed

•Water Temp

•Oil Temp

•TransmissionTemp

•AC Ref.Pressure

•IAT Temp

•Ambient Temp

•Vehicle Speed

100% Duty CycleIf…

•Coolant exceeds260 degrees.

•Trans Oilexceeds: 300degrees.

•AC pressuresexceeds 240 psi.

The fan iscommanded toless than 100%under all otherconditions.

Actuation ofthe Solenoid

Valve!

Ford &Chrysler use

a Rotarysolenoid

20 Hz Rate ofchange

Commonalities With GM?

Ford/Chrysler Clutch ActuationCommonalities

As where GM uses a Linear control…

Ford and Chrysler use rotaryactuation.

This type of control is the sameconcept as a thermostatic spring.(Only far more complicated)

Auxiliary Electrics

Dual Fan Applications…

Many Vehicles usemultiple fans. Thisapplication uses asupplementalelectric fan whenAC is requested.

The primary coolingis preformed by athermostaticviscous fan clutch.

Placement of an Auxiliary Fan

Mount an auxiliary fan in a locationoff center from the radiator?

If we center it, it may have animpact on the performance of an OEmounted thermostatic fan clutch.

a temp controlled fan (controllerinstalled) affords ram air to be moreefficient when cruising speed isattained.

Air Flow Calculation

What kind of air flow can begenerated with the effect ofram air?

A 2FT X 2 FT Radiator at 10miles an hour?

Flow is equal to volume timesthe area… Q= F*A

Which is:10 X 5280 = 880 X 4 = 3520 CFM

60

CFM- what is it?

Cubic Feet per Minute It is the volumetric airflow of a fan. In our industry, catalog specifications measure the airflow (CFM) at

zero pressure.

Air Flow (CFM)

Pres

sure

CFM at 0pressure

Fan Characteristic Curve

Air Flow (CFM)

Pres

sure

Pressure whenthe fan is totallyblocked

Airflow whenthe fan is totallyopen with norestriction

Typical Fan Operation

CFM- What it is not!

It is not an indication of BTU’s per min or actual cooling It is not the actual airflow through a cooler, radiator, or condenser Actual cooling CFM depends on a number of factors, mainly the

restriction or pressure the fan has to overcome to work…

Air Flow (CFM)

Pres

sure

CFM at 0pressure

CFM1

SystemRestrictionCurve

Fan Curves & Restriction Curves

Air Flow (CFM)

Pre

ssur

e

CFM at 0pressure

CFM1 CFM2 CFM3

Restriction1

Restriction2

Restriction3

Fan Curve

The same fan runs at 3 different CFM ratings in 3 differentapplications

Sources of Restrictions

The Heat Exchanger Thickness of radiator , condenser or oil cooler Number of cores Fin density Fin thickness

The Application Grill and vehicle geometry Recirculation Ram Air and vehicle speed

The Fan Assembly Shroud Geometry and solidity Number of fan blades or solidity of Fan blades Finger Guards

Anything that impedes open airflowAnything that impedes open airflow

Fan Curves and the Myth

Fans can be high pressure or low pressure by design and will providedifferent CFM ratings with the same restriction curve

• In a Catalog: CFM Low pressure fan = 2x CFM High pressure fan

Air Flow (CFM)

Pres

sure Catalog

CFM

CFM1 CFM2

High Pressure Fan

Low Pressure Fan

However, Actual CFM1 < CFM2

High Pressure Fan

High restriction applications High fin density Multiple heat exchangers stacked

in series

High pressure fans have highersolidity Applications where ram air is not

as significant for engine cooling

When do you use a high pressure fan?

High restriction applications Multiple core, thick radiators High fin density Multiple heat exchangers stacked in series

Restriction does not vary Same CFM can be obtained over operating conditions i.e. 8” oil cooler mounted away from front of vehicle

High pressure fans usually have highersolidity Applications where ram air is minimal or have little effect

When do you use a low pressure fan?

Low restriction applicationsSingle core, thin radiators or condensersLow fin densitySingle heat exchangers not stacked inseries

Restriction does vary due to ram airRam air varies restriction curvesAuxiliary Condenser fans

Low pressure fans usually have lower solidityApplications where ram air is significant forengine cooling

Fan Curves & Restriction Curves

Restriction3

Air Flow (CFM)

Pre

ssur

e

CFM1CFM2 CFM3

Restriction1

Restriction2Fan Curve

Restriction 1 (High): Radiator, Condenser and OilCoolerRestriction 2 (Med): Radiator, Condenser

Restriction 3 (Low): Condenser

Typical catalog data shows no restriction: Lower than low

Does Catalog CFM Matter?

Air Flow (CFM)

Pre

ssur

e

CFM1

Low Pressure Fan

Idle

30 MPH

50 MPH

CFM2

• At Idle conditions, and with 2different CFM rated fans the sameairflow can be provided.

• However, at 30 MPH the higherCFM rating may provide someadditional airflow…

BTUs per min

Defined as Heat rejection capacity Factors that change BTUs/min

Fin size Fin Density Fan coverage Airflow distribution Number of cores Actual airflow not catalog airflow

Alternatives….

Some alternative coolingoptions have shown up in theaftermarket.

However, it might not be forevery customer application

This retro touts a savings of11 MPG

QUESTIONS?

On Behalf of Hayden

Thank you!