turolla-hyfandr

7/30/2019 Turolla-hyfandr

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OpenCircuitGeaMEMBER OF THE SAUER-DANFOSS GR

Sponsored by

Presented b

a wise investmentin many ways

Belt driven fans have been the mostcommon method of cooling vehicleengines for more than 100 years.They’ve retained their widespread

use because they are simple and reliable.

After being aligned by the engine manufac-turer, belt drives give years of trouble-freeservice life. However, as emission standardscontinue to become increasingly more de-manding, vehicle designers must find inno-vative new ways to cool engines. First, they must develop more efficient cooling systemsbecause reducing the power draw for cool-ing reduces the engine’s fuel consumption ormakes more engine power available for workfunctions. Second, engine temperature pres-ents a strong influence on a diesel engine’s

fuel consumption and output of emissions.So controlling the engine’s operating temper-ature within a narrow range can reduce bothemissions and fuel consumption.

Benefits of belt drivesBelt drives are durable and from an ini-

tial cost standpoint, the most economicalmeans of power transmission. The simplestdrives consist of one or more belts and a setof sheaves (pulleys). Once properly installedin a vehicle, a belt is rated for thousands of hours or tens of thousands of miles of opera-

tion — and the sheaves usually last the life of the engine.Belt drives are also efficient. When op-

erating at their peak of performance, they can deliver 90% or more of the power they transmit from the driving shaft to the driven.However, the belt drive itself doesn’t promoteheat transfer — the fan does. And a rotat-ing fan uses a substantial amount of power,whether it is running with the engine idlingor operating at high speed. The faster it spins,

the more air it pulls through the cooling sys-tem’s radiator, and the more engine power —fuel — it consumes.

Belt-driven cooling systems

Belt drives have served industry well, butwith so much attention placed on higher effi-ciency and lower emissions, cooling require-ments for today’s engines are beyond thecapabilities of belt drives except for only theleast demanding applications. Even car man-ufacturers have switched from belt-drivento motor-driven fan drives. But effective andefficient cooling systems are even more im-portant for both off- and on-highway equip-ment because the power needed to provideadequate cooling is greater. Furthermore,

increasingly stringent emissions standards

Hydraulicfan drives

Tom Modica, ProductApplication Engineer

Matt Kronlage, ProductApplication Engineer

1 TurollaHydraulic fan drives

Beltdriven fanassembly

ThermostatIn-cabheater

core

Water pump



and its application tgenerate a signal tothe electrohydrauli valve. The valve reaby increasing or de-creasing the hydraupressure across themotor based on the

proportional com-mand signal. Highepressure equatesto higher availabletorque to turn the ffaster.

Because the sig-nal and the valve arproportional, the facan rotate anywherwithin its range of minimum and maxmum speed allowed

by the electrohydraulic program. When the vehicle’s enginis first started, the fan typically does not need to be rotat-ing. This allows the engine to reach operating temperaturemore quickly than if the fan was pulling cold air through thradiator, which is normally the case with belt-driven fans.Therefore, the hydraulic fan drive does not waste power bydriving the fan when it’s not needed and does not overcoolthe water, so less fuel is burned and fewer emissions are re-leased to the atmosphere.

On the other hand, when the engine requires peak heatrejection and maximum fan speed (which typically occursonly about 1% of a vehicle’s operating life), the electronic co

trol unit signals the electrohydraulic pressure control valveto maximum pressure. An axial fan moving air develops atorque load that is proportional to the square of the speed othe fan. Because motor torque is proportional to the hydralic pressure across it, regulating hydraulic pressure provideprecise method of controlling fan speed.

The ECU provides proportional fan speed control basedon water temperature, ambient temperature, or other key prameters. The result is much more precise control of engintemperature than is possible with a belt drive system. This especially important with diesel engines because operatingtemperature has a two-fold effect on diesel engine perfor-mance. First, a diesel engine’s power-to-fuel consumption

ratio peaks within a relatively narrow range of temperatureSecond, the emissions released per pound of fuel used is lowest within another narrow range of temperatures. These twratios overlap within an even narrower range, so operatingthe engine within this narrow range of temperatures providhigher fuel economy and lower emissions.

Test shows quick returnon investment

Because they have a lower average power consumptionthan belt-driven fans and keep the engine operating at its o

require tightercontrol of enginetemperature.

Belt drives havebeen the primary means for drivingcooling fans becausethey are familiar, in-

expensive, and some-what maintenancefree — even if they aren’t particularly ef-fective or efficient.The problem is, belt-driven fan drives pullair through the ra-diator all the time, re-gardless of how muchor how little coolingthe engine needs. Thisis because belt drives

operate at a fixed speed ratio to the engine speed. Wheneverthe engine is running, so is the fan. And the faster the engineruns, the faster the fan runs. This is not the most effectivemeans of cooling because the power needed to drive the fancomes from the engine. Power equates to fuel consumption,so the belt drive consumes engine power whether cooling isneeded or not. Furthermore, an engine running at full speedmay not necessarily be operating at full load. Likewise, an en-gine under full load running at moderate speed may overheatif the fan is also operating at moderate speed.

A more effective andefficient alternative

Hydraulic fan drives have emerged as a more effectiveand efficient means of engine cooling because fan speed isdetermined by engine cooling demand, not engine speed.The result is that the hydraulic system drives the fan at theprecise speed required to provide only the amount of air flow needed. This means the fan is not wasting energy by rotatingfaster than it needs to, just because the engine is running athigh speed. Furthermore, hydraulic fan drives take advantageof the functionality and other benefits hydraulic systems canadd that are not possible with belt driven fans.

Hydraulic fan drives are usually specified from standardcomponents to serve the particular needs of a vehicle and its

application. But for simplicity, a basic fan drive consists of ahydraulic gear pump to transmit the hydraulic power (flow and pressure) to a hydraulic gear motor, which drives the fan.An electronic control unit (ECU) monitors vital parametersand commands an electrohydraulic pressure-control valve toregulate the amount of power transmitted to the hydraulicmotor. The ECU can receive inputs from temperature sen-sors that monitor ambient air temperature, coolant tempera-ture, fan speed, and other relevant parameters. Typically, only water temperature is monitored to control fan speed. TheECU then uses a program developed for the specific vehicle

2 TuroHydraulic fan drives

Can BusMicrocontroller

(Plus+1™)

Temperaturesensors T1,

T2, T3

T1

T2

T3SGM2VC aluminum

fan drive motorwith integratedreversing valves

Case drain

Enginecontrolmodule(ECM)

Deisel engine

Gear pump (D series)

ReservoirFilter



Fan drive speed comparison

F a n

s p e e d - r p m

1500

1000

500

0

Time of day

2 : 0 0 : 0 9

2 : 0 6 : 0 0

2 : 1 1 : 2 7

2 : 1 6 : 5 1

2 : 2 5 : 5 1

2 : 3 1 : 1 5

2 : 3 8 : 0 9

2 : 4 2 : 0 0

2 : 4 7 : 2 7

2 : 5 2 : 5 1

2 : 5 9 : 1 5

3 : 0 0 : 0 9

Fan speedwith belt drive

Fan speedwith hydraulic drive

still runs faster than the hydraulic fan duringmost of the work cycle and when the engine is

idling.Rotating the belt-driven fan at a higher

speed than necessary wastes fuel, even at idle.With the engine idling, the belt-driven fanrotates at the same speed whether the ambi-ent temperature is high or low. This is becausethe fan must rotate fast enough to provide ad-equate air flow during hot weather. However,during cold weather, the higher speed simply wastes engine power, which equates to wastedfuel or wasted productivity. The hydraulic fan,however, always runs at a speed based on cool-

ing demand rather than engine speed.The fuel savings equates to 1.62 gal/hr.

timum temperature for fuel economy, hy-draulic fan drives can quickly pay for them-selves in fuel savings alone. How much,of course, depends on the application. Acontrolled test program was conducted tocollect data for quantitative analysis of a hy-draulic fan drive cooling system. Tests wereconducted using a Terex 50-ton Payhauler

mine truck equipped with a Cummins1710 (725 hp @ 1800 rpm) diesel engine ata quarry. Tests used the same driver, overthe same route, and on consecutive days toensure nearly identical test conditions. Thevehicle was fitted with sensors to monitorengine coolant temperature at multiplelocations, ambient temperature, fuel flow,hydraulic fluid pressure, and other relevantparameters. A standard route with the sameoperator was used for consecutive periodsto limit test variables. Inputs from eachsensor were programmed into electronic

controls to capture information during thedaily operating cycle of the vehicle. Afterdata were collected from the vehicle withits conventional system, the hydraulic fandrive system was installed. Output from theelectronic control unit was programmed toincrease or decrease pressure of the motorcircuit based on coolant temperature.

Fuel consumption was captured withan in-line fuel sensor for both system set-ups, and test results are shown in the table.They show that the hydraulic fan drive not

only reduced fuel consumption by 14.5%,but also improved cycle time by nearly 8%.These improvements are based on the hy-draulic fan drive reducing fuel consumptionfrom 167.4 to 143.1 gal and increasing thenumber of dumps from 72 to 78 in 15 hr.

The graph shows plots of a typicalsingle run using both technologies. Theupper plot, orange, represents fan speedwith a conventional belt drive. Fan speedstarts with the engine idling, then beginsfluctuating at around 2:17 PM. The speedfluctuates because the engine is constantly

accelerating and decelerating as the drivertravels his route. The speed peaks at 1000rpm or higher five times during the routerun, which ends at about 2:50 PM.

The lower plot, blue, represents fanspeed using a hydraulic drive. Again, thedriver began his route at 2:17 PM andended at about 2:50 PM. The speed ratio of the belt drive rotates the fan at only about45% of the engine’s crankshaft speed. Evenat this reduced speed, the belt-driven fan

Summary of test resultsHydraulic fan

driveBelt driven

fan

Days of tests Feb 25 & 26 Feb 26 & 27

Hours of operation each day 9 & 6 9 & 6

Total engine run time 14.7 hr 14.7 hr

Number of work cycles 78 72 Time between work cycles* 11.5 min 12.5 min

Fuel consumed 143.1 gal 167.4 gal

Fuel consumption rate* 9.54 gal/hr 11.16 gal/hr

Fuel used per work cycle* 1.83 gal 2.31 gal

* Average values from all test runs Two-day tests show hydraulic fan drive cut fuel consumption by 14%

3Turolla Hydraulic fan driv



bris from the radiator, which can reduce cooling efficiencymuch as 50%. This feature is especially useful in applicationwhere the vehicle operates in particularly dirty environmeand can reduce the need for screens, which add cost andsize to the radiator and can restrict air flow. The reversingfeature can also blow water out of the radiator to preventdamage from freezing in cold climates. Reversing can occuon-demand whenever the operator presses a switch, or it c

be programmed into the ECU to occur at regular intervalsReversing also improves productivity by eliminating theneed for someone to periodically clean the radiator.

Another advantage is design flexibility. Because the hy-draulic fan motor is connected to a pair of hoses, rather tha belt drive attached to the engine, the radiator and fan canbe placed anywhere on the vehicle. Placing the radiator andfan elsewhere makes space available for other componentsinside the engine compartment — which is important fordesigners who consider space precious in meeting Tier IV and Stage IV requirements. Plus, the engine compartmentmay not be the best place for a radiator because the ambie

air drawn in by the fan may be hot and dirty. Instead

the radiator and hydraulic fan may be placed in location of the vehicle where ambient air is cooand cleaner. This flexibility also lends itself to

distributed cooling designs, so coolers can be sttegically sized and located throughout the vehicfor optimum performance and efficiency.

Hydraulic fan drives can also provide brief power boost functionality to the engine. Th

is done by programming theECU to actuate valves to putthe pump and motor in a netral condition on command

Power consumption of thefan drive is essentially elimnated — power that now ca

be used by the engine to booacceleration or provide more

muscle for work functions. Abig advantage to power boost for equipment

designers is that it may allow a smaller engineto be used. This is important because increas-

ingly strict regulations cause more and moreengine power to be used for emissions, rather

than for work or propulsion. Consequently, largerengines are needed. However, a power boost func-

tion may offset power requirements enough that usinglarger engine may be avoided.Moreover, hydraulic fan drives can be integrated into

other vehicle systems or provide power for auxiliary func-tions, which is not possible with belt driven fan drives. Forexample, excess power capacity from the fan drive’s pumpcan provide hydraulic power to assist other functions

In fact, the hydraulic fan drive can even reduce energy aextend brake life. By incorporating the fan drive into the vehicle’s braking system. The hydraulic fan circuit would helpdecelerate the drive train by converting momentum of the

With a two-shift work schedule at 80 hr/week, 50 weeks peryear, this represents a potential savings of 6,480 gal of fuelper year. Even with a conservative fuel cost of $3.00/gal, thepotential exists to reduce annual fuel cost by nearly $20,000per vehicle. Total installation cost to retrofit the hydraulicfan drive was less than $6,000 per vehicle. Therefore, returnon investment for retrofitting the vehicle was about fourmonths.

However, tests showed the hydraulic drive does morethan save fuel and increase productivity. Based on laboratory test data for standard diesel emissions, emission values werecalculated as a result of reduced fuel consumption for thistest program. These calculations indicated that the hydraulicdrive reduced NO

Xemissions by 6.8 lb per 10-hr shift. This

calculation doesn’t even account for the additional decreasein emissions by operating the diesel engine at optimumtemperature.

Engine and fan speed covered a time period from 6 AMto 4 PM for both types of systems. As would be expected,less power was needed for cooling in the morningthan in the afternoon. For example, test data

revealed that the hydraulic fan drive requiredabout 6 hp for cooling from 6 AM to 8 AM,whereas 9 hp was needed from 2 PM to 4 PM— evidence that the hydraulic fan drive auto-matically provided more cooling power asambient temperatures climbed through-out the day. Nevertheless, coolanttemperature consistently maintainedbetween 180° and 185°F.

After the vehicle had been retro-fitted with the hydraulic fan drive,the operator stated that he im-

mediately felt more power at initialacceleration under full load. This canbe explained by examining the superim-posed plot of engine and fan speeds.The plot shows that fan speed of aconventional system rises and fallswith engine speed. With the hydraulicfan drive, however, average fan speedis lower than with a conventional cool-ing system. When the engine was notidling, average speed was 1,600 rpm withthe conventional fan, but only 600 rpm withthe hydraulic fan drive. Because lower fan speed

requires lower torque, the hydraulic fan drive con-sumes less power from the engine. Therefore, more power isavailable to do work. This increased power accounts for thereduction in work cycle time.

Additional functionality Hydraulic fan drives have proven to be more than a wise

investment due to fuel savings and reduced emissions. If thehydraulic circuit is equipped with a flow-reversing valve, thehydraulic motor can rotate in the opposite direction to pushair out through the radiator. This is done to purge dirt and de-

4 TuroHydraulic fan drives



efficiency, and reliability. Fan drive engineering tools helpTurolla experts design systems that deliver the highestperformance and efficiency for the quickest return on investment. These tools are also available to trained Turolladistributors, and Turolla system designers also share theirexperience by providing training so that original equipmenmanufacturers and hydraulic distributors will understand toperation and advantages of hydraulic fan drives.

Sizing up the optionsAs with any new technology, hydraulic fan drives may

not seem like a viable alternative to some designers. Thosesimply looking only for the lowest initial cost will still findbelt drives the power transmission method of choice. But fthose looking for a solution that will pay for itself many timover through higher productivity, higher fuel economy, lowemissions, and many more potential benefits, hydraulic fandrives present an option offering big savings for their com-pany or their customers. Combine these features with theability to integrate the ECU with electronic engine and othcontrols (such as the PLUS+1 System) and you can be conf

dent the entire machine will deliver optimum performanceefficiency, and productivity.To fully capitalize on the many benefits offered by hy-

draulic fan drives, they should be designed as a systemfor the specific application in which they will be used.By relying on a reputable supplier offering a full compli-ment of system options ensures that the most effective,efficient, and economical system is provided. For moreinformation on fan drives or assistance in sizing a solutionfor your needs, call (515) 239-6677, email [email protected] visit www.TurollaOCG.com.

vehicle by dispersing the excess power into thehydraulic fan motor, thereby relieving a portionof the load on the brakes.

Hydraulic fan drives also make it easier tomeet more-stringent noise legislation. This isbecause the fan in proportional drives is tested atonly 70% of maximum speed. And because noisegeneration is not proportional to fan speed, ro-

tating the fan 30% below maximum speed resultsin more than a 30% reduction in noise.

Multiple benefits ofelectronic control

Higher fuel economy and lower emissionsalone make electrohydraulic fan drives a wiseinvestment. But the benefits of closed-loopelectronic control offer many more benefits. Forinstance, the ECU constantly provides conditionand fault monitoring and instantly alerts the op-erator to any malfunctions it detects. In fact, thecontrol calculates and can display power draw of

the fan drive at any time for maximum perfor-mance, efficiency, and productivity.

The ECU also allows the operator to manually override control at any time from within the cab.If a situation calls for a quick power boost of the engine orto blow out debris drawn into the radiator, the operator cancommand the ECU to take appropriate action. Furthermore,if the ECU is integrated into other primary or auxiliary elec-tronic controls, its action can take into account the condi-tions of other systems.

Why Turolla OpenCircuitGear hydraulic fan drives?

As already pointed out, hydraulic fan drives hold multipleadvantages over belt-driven systems. So why not just put asystem together yourself from available components or letone of your regular suppliers put one together? Even a hastily assembled system using the cheapest components availableshould still quickly pay for itself, shouldn’t it?

Not necessarily. All components for a fan drive should beselected and sized to the specific application. A mining truckhas different cooling requirements from an excavator, whichhas different requirements from a harvester or marine drive.So choosing a source with expertise in engineering hydraulicfan drives, such as Turolla, ensures having a system best-

suited to the equipment and its application. Turolla’s 40+years of expertise goes beyond just knowledge of hydraulicsor electronics. Turolla’s team of experienced engineers andtechnicians has knowledge and experience in hydraulics,electronics, control, cooling systems, and Tier and Euro emis-sions standards to provide the best possible experience forselecting and sizing hydraulic fan drives.

Turolla offers products designed and manufactured spe-cifically for hydraulic fan drives. This means pumps, motors,valves, and controls have been optimized for hydraulic fandrives, so the systems will deliver optimum performance,

5Turolla Hydraulic fan driv

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