why electronic fan clutches - motor · pdf filewhy electronic fan clutches. ... centrifugal...
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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!