Application Example:Testing of torsional vibration dampers.Measurement of torsional, axial andradial vibration modes.

Advanced Telemetry Systems for Automotive Testing

New measurement instrumentationtechnologies are rapidly reducing vehicledevelopment program schedules byoffering efficient tools to measure andrecord data in component test standsand dynamometers as well as test trackapplications.

For many years wear-susceptiblesliprings and very basic, user unfriendlytelemetry systems were the standardinstruments for taking measured datafrom rotating vehicle components.Today an advanced wireless telemetrytechnology, combined with expertapplication engineering and after salesservice, is available from datatel and isleaving the traditional solutions farbehind with regard to reliability, wear,reproducibility, accuracy and ease of use.

Telemetry transmitter with integral accelerometers

Rotor coil/antenna

Stator coil/antenna pick up

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Product Profile

Product Profiledatatel telemetry products are theresult of more than twentyfiveyears of continuous user-orienteddevelopment and cover a widerange of rotating and reciprocatingapplications including automotive,test stand, transmission, railroad,process industry, turbomachineryand aerospace installations.Systems have been delivered withcapacities ranging from a singlechannel to several hundred chan-nels in one installation.Miniaturized telemetry transmit-ters are available for all standardmeasurement sensors for staticand dynamic strain, torque, force,temperature, pressure, acceleration,vibration, displacement etc. How-ever, datatel is always ready todevelop or modify a special trans-mitter for the customer’s require-ment, together with the associatedreceiver and signal conditioning.

upon the performance of the sen-sors being used, but with datateltelemetry a measurement accu-racy of ± 0.1 % FS can be achieved.In addition these modern tele-metry systems feature helpfultools such as remotely controlledinstrumentation diagnosticfunctions (e.g. online strain gageshunt calibration and auto-zerofunction, thermocouple ‘open’detection, programmable gain and transmitter power supplymonitoring) to check out thecondition of the sensor and thecomplete measuring chain.

As a result of SMD, COB andHybrid technology combined withspecial module packaging andpotting methods these telemetrytransmitters can accept operationin harsh conditions such as –40°Cto +125°C, g-loads more than100,000g, shock, vibration, oilyand gaseous environments.

Datatel telemetry uses state-of-the-art analog and digital techno-logy. Even highly dynamic signalsup to 50 kHz frequency responsecan be measured and transferredwith excellent quality and accu-racy. The data from each individualtransmitter are transferred to thetelemetry receiver unit at a select-ed radio frequency in the MHzrange. The final accuracy of thedata is also, of course, dependent

Advanced Telemetry Systemsfor Automotive Testing

Sensor Telemetry Receiver

Power Supply

Telemetry Transmitter

S/G T/C ICP Amplifier Converter Transmitter Receiver Converter Amplifier

Battery Inductiveor

Sensor Excitation

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of test components and the appli-cation of sensors (eg. strain gag-ing services). Particularly impor-tant are custom transmitter carri-ers and inductive power coil/antenna assemblies, produced tosuit the special requirements ofany application. Hence the tele-metry components are not merely‘tacked-on’ to the machine undertest but are fully integrated intothe mechanical design so as toensure secure, prolonged opera-tion. For major test stands thisprovides virtually a permanentinstallation. Final system assem-bly, checkout and test is carriedout at the datatel plant wheneverpossible, but on-site support isalways available.

Telemetry receivers are availablewith analog or digital output andcan be connected directly to thepreferred data acquisition system.Output signals are already fil-tered, amplified and calibrated.No additional signal processing ofthe measured data is needed.

To meet even the limited spacerequirement of test vehicle appli-cations, receiver units are avail-able as compact, self-sufficientunits. They are rugged and can be powered by on-board 10 to 36VDC. Alternatively for test standsand laboratory installations, re-ceivers in modular 19“rack techno-logy with mains power supply arestandard.

All datatel telemetry transmitterscan be powered either by batteryor inductively. This dual powerconcept ensures the highest levelof flexibility for a wide range ofapplications.

Battery supply can be used underthe following conditions:

� Short operating times (several hours to a few days)

� Good accessibility � Sufficient space� Suitable for rotating or freely

moving test objects.

Customized Turnkey Solutions

Transmitter carriers forinstallation on differentshaft diameters

Inductive power supply is main-nance-free and can be used underthe following conditions:

� Long-term measurements(over weeks, months or years)

� Poor accessibility� Limited space requirements� Suitable for rotating test

objects even for very high rotating speed.

An inductive power supply workslike a transformer and has a sta-tionary and a rotating coil. The coilsystem is fed by a power genera-tor. The antenna system for thedata transmission is built into therotor and stator coils. datatel cansupply a wide range of ready-to-install standard or customer speci-fied coils set.

Customized Turnkey Solutions

datatel telemetry is based upon a highly-developed, modular elec-tronics technology, supported byall the skills and resources neces-sary to design, manufacture andintegrate complete, turnkey solu-tions to customer measurementrequirements. This includes thedesign and fabrication of all spe-cial hardware needed for theapplication, plus the modification

Custom design telemetry transmitter for strain measurement in a gear wheel

The result is targeted custom-designed turnkey telemetry systemsfrom a single source. The unusuallywide range of services and technicalsupport provided is beneficial forthe test program and guaranteessuccess even for the most sophisti-cated telemetry projects.

AutomaTorqueTemperatOil pressu

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Automotive Testing Applications

Automotive TestingApplicationsThe versatility of datatel telemetryis a door-opener for a variety ofnew applications and makes itindeed a powerful tool for vehicletesting engineers. Some exampleswill demonstrate the flexibilityand efficiency of these advancedwireless measuring devices:

rings is required and the systemcan be used in public traffic.Moreover the installation can beperformed within minutes.

For permanent torque monitoringthe battery can be replaced by amaintenance free inductive powersupply (see Photo 1). The telemetrytransmitter and the rotor induc-tion pick up is completely sealedin a clamp-on carrier device and is protected against dust, watersplash or snow. The wide statorinduction loop allows sufficientfreedom of motion of the cardanshaft.

1: Torque measurement on a truck cardan shaft

Drivetrain Torque Measurement

A standard requirement in vehicletesting is torque measurement ondrivetrain components like half-shafts and cardan shafts. For short-term measurements battery pow-ered telemetry transmitters can beeasily attached with a strain gageto the rotating shafts. The meas-ured torque data is transmitted via radio frequency to the receiverunit inside the vehicle cabin. It isbeneficial that no external mount-ing device as familiar with slip-

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DamperVibrationTemperature

EnginePiston temperatureConrod forceBearing temperatureTorque and strain on crankshaftTorque on camshaft

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Flex PlateEngine torque

Gear BoxTorqueTooth force

ClutchTemperatureForce

Brake DiscTemperature

4Fuel Injection PumpTorqueForce

AlternatorWinding temperature

TurbochargerBlade vibrationsTemperature

TireTemperaturePressure

atic Transmission

ureure

Drive ShaftTorque

Automotive Testing Applications

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Temperature Measurementin Automatic Transmissions

Photo 2 shows a telemetry appli-cation to measure temperature inan automatic transmission. Withthe given space limitations andthe severe operating conditions itis almost impossible to integrate a standard slipring or telemetrysystem components. A customdesigned 8 channel telemetrytransmitter with thermocoupleinput was developed to meet therequirements. A flat, ring-shapedtransmitter carrier and rotor in-duction coil assembly is mountedon a modified reverse clutch hubwith the stator coil attached tothe pump plate. The sealed tele-metry electronics withstands theagressive transmission oil operat-ing temperature of up to +125°Cand reliably measures accuratetemperature data from the fric-tion plates for months. Furtherapplications inside transmissionand gear drive components are eg. telemetric temperature, force,torque and oil pressure measure-ments.

2: Temperature measure-ment in an automatictransmission

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Cardan ShaftTorqueTorsional vibration

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Steering SystemSteering torqueSteering force

A/C CompressorTorque

Wheel/RimWheel forcesWheel moments

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Automotive Testing Applications

Telemetry Systems for Road Load Data Acquisition

A detailed knowledge of the dyna-mic forces input to a roadwheelduring operational usage plays animportant role in both the designand validation processes of a newvehicle. With multi-axial wheelforce transducers it is possible toacquire road load data such aslongitudinal, lateral and verticalforces and the respective momentsintroduced into the rolling wheelunder operational conditions.

An 8 channel telemetry system isused to transmit the signals fromthe strain gage based wheel forcetransducer (see Photo 3). More-over the telemetry system handlesonline the processing of the meas-ured data.

The telemetry transmitter featuresintegral rotation angle measure-ment, two additional spare chan-nels for brake or tire temperature

measurement, a special sensorconnector interface to ease theassembly and connection with the wheel force transducer instru-mentation and on-board sensorcalibration circuitry.

Temperature Measurementon Brake Test Stands

Telemetry solutions for automo-tive component test stands are ofinterest to replace conventionalslipring installations to improvethe performance regarding relia-bility, signal quality and accuracyfor long term test programs.

A typical example is temperaturemeasurement on brake test stands(see Photo 4). An inductivelypowered multi-channel telemetrysystem is mounted on the shaftof the test rig using a customizedsplit transmitter carrier for easyclamp-on installation. Upgradesfor existing test stands are avail-able. The telemetry transmitter is

equipped with a screw terminalinterface for thermocouple hook-up, no soldering is required. Theintegral thermocouple "open"detection reliably indicates brokensensor wires.

CamshaftTorque Measurement

Photo 5 shows a telemetry instal-lation on a camshaft test stand.Torque and rotation angle aremeasured on both camshafts by

special strain gage based torquetransducers and angle transducers.The transducer/telemetry assem-bly is attached to the shaft endand a radially mounted inductivecoil/antenna system picks up thetransmitted torque data.

5: Torque measurement on a camshafttest stand

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3: 6-component wheel force transducerwith telemetric data transmission

4: Temperature measurementon a brake test stand

Piston Temperature andConrod Force Measurement

The knowledge of piston tempe-ratures during fired engine opera-tion represents important infor-mation for the development ofmodern combustion engines. Inorder to provide this data a specialtelemetry system was developedto enable online piston tempera-ture measurements. A telemetrytransmitter with a miniaturepower conditioning/storage system and a rotor coil/antennapickup is attached to the conrod(see Photo 6). The transfered RFsignals are picked up by a statorpower coil/antenna mounted on the engine block.

With this system temperaturemeasurements under all operatingconditions of engine speed andload are possi-ble. Moreover,other para-meters likepressure,pistonring displacementand forces on the conrodcan be meas-ured with asimilar tech-nology.

CompanyBackground

Telemetrie Elektronik GmbH(datatel) wasfounded inHannover,Germany in 1976.The philosophy of providing expertadvice to ourcustomers coupledwith the highperformance, relia-bility and ease ofuse of the productshave made thecompany into oneof the leadingmanufacturers oftelemetry systemsWorldwide.

datatel telemetry systems have beensetting new standards for the linkbetween rotating or moving sensorsand stationary data acquisition sys-tems. The team of 40 experiencedemployees is specialized in the design,development and manufacture ofinnovative turnkey solutions for tele-metric measurements of all kinds. Inaddition, a wide range of service andsupport activities is provided.

datatel is represented internationallywith a network of service and salespartners in Europe, Asia and NorthAmerica.

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6: Piston tempera-ture measurement

www.datatel-telemetry.com Telemetrie Elektronik GmbHBerliner Allee 42D-30855 Langenhagen · GermanyTel. +49(0) 511 97 83 96-0Fax. +49(0) 511 97 83 96-16sales@datatel-telemetry.de