measurement of running resistance by …€¦ · measurement of running resistance...

A.Müschen, E.Dewulf, P. Bailey, C.Hosier

MEASUREMENT OF RUNNING RESISTANCE BY

TORQUEMETER METHOD

redmann

Stempel

� Measurement of Running Resistance

� Chassis-Dynamometer Setting

� Comparison Torquemeter Method / Coastdown Method

2 11/12/2012 Torquemeter-Coastdown_Comparison of Methods

TORQUEMETER METHOD


• Torquemeter in the drive-train of test

vehicle to measure running

resistance

• Preferably: measure running

resistance at the rims of each of the

driven wheels

• Excluding effects of powertrain /

transmission / vehicle inertia during

measurement

• Instrumentation of vehicle w/o

affecting running resistance

(aerodynamic drag)– special set of rims and adapter rings

– signal transfer to data collection device,

preferably wireless

– difficult / time consuming

Wheel

Position of StrainGauges

TorquemeterMeasuring Device

Adapter

Brake Disc

MEASUREMENT OF RUNNING RESISTANCE - ROAD TESTING (1)


Vehicle conditioning:

• Preconditioning and Stabilization of vehicle at the speed where the running

resistance is to be measured

Torque Measurement / Data Collection (ISO 10521-1):

• Record at least 10 data sets of speed/torque/time for min. 5 seconds, see table

• Calculate mean speed and torque

• Assess accuracy of measurement

• Repeat torque measurement on the track in both directions to have at least 4

consecutive results with sufficient accuracy

MEASUREMENT OF RUNNING RESISTANCE - ROAD TESTING (2)


Torque Measurement / Data Collection (ISO 10521-1):

• …

• Determine Running Resistance Curve

• Correct to Standard Atmospheric Conditions

LOAD SETTING OF CHASSIS DYNAMOMETER (1)


Wheel



Adapter

Brake DiscEvaluate Dyno Setting to provide same

torquemeter readings vs. speed

as measured on the road (“running resistance”)

• Vehicle is fitted with the same

instrumentation as on the road

• Preconditioning and Stabilization of vehicle

at the desired speed

� Dyno Adjustment / Data Collection:

• Record at least 10 data sets of

speed/torque/time for min. 5 seconds,

see table

LOAD SETTING OF CHASSIS DYNAMOMETER (2)


Wheel



Adapter

Brake Disc� Dyno Adjustment / Data Collection:

• Calculate mean speed and torque

• Assess accuracy of measurement

• Repeat torque measurement to have

at least 4 consecutive results with

sufficient accuracy

• Determine Road Load Resistance Curve

• Verify road load setting,

error of simulated road load to be

< 10% up to 20km/h, < 5% up to 50 km/h,

< 3% else

• if required: Adjustment of dynamometer coefficients & new Iteration

Chassis dynamometer setting process – Verification

Vehicle, Dyno

Tyre

Details

ROAD LOAD COMPARISON C/D MATCH VS. TORQUEMETER METHOD (1)


Road load comparison between the torque method and the coast down method

Tyre Rdyn. Weight IWC Track Torque (Nm) Dyno load (N) Coast Down Data derived from Dyno Settings ( sec )

a b c F0 F1 F2 125-115 115-105 105-95 95-85 85-75 75-65 65-55 55-45 45-35 35-25 25-15 TOTAL

(m) (kg) (kg) 120 110 100 90 80 70 60 50 40 30 20

235/50R18 0,336 1768 1810 62,0 0,091 0,01349 102,1 -0,015 0,0405 5,83 6,58 7,45 8,48 9,68 11,09 12,70 14,53 16,53 18,60 20,56 132,03

Tyre Rdyn. Weight IWC Track Coast Down Data ( sec )

125-115 115-105 105-95 95-85 85-75 75-65 65-55 55-45 45-35 35-25 25-15 TOTAL

(m) (kg) (kg) 120 110 100 90 80 70 60 50 40 30 20

235/50R18 0,336 1768 1810 5,77 6,53 7,40 8,44 9,64 11,07 12,70 14,54 16,56 18,64 20,60 131,89

Speed [km/h] 120 110 100 90 80 70 60 50 40 30 20

calc. Force, based on TorqueMeter Method, [N] 862,4 764,1 674,9 592,9 519,4 453,4 395,9 346,0 304,2 270,3 244,5

calc. Force, based on Track Coast Down Method, [N] 871,4 770,0 679,4 595,7 521,6 454,2 395,9 345,8 303,6 269,7 244,1

Force Difference (TorqueMeter - Track c/d) [N] -9,0 -5,9 -4,6 -2,8 -2,2 -0,8 0,0 0,2 0,6 0,6 0,5

rel. Difference [%] -1,0 -0,8 -0,7 -0,5 -0,4 -0,2 0,0 0,1 0,2 0,2 0,2

time Difference (TorqueMeter - Track c/d) [sec] 0,060 0,050 0,050 0,040 0,040 0,020 0,000 -0,010 -0,030 -0,040 -0,040 0,140

rel. Difference [%] 1,0 0,8 0,7 0,5 0,4 0,2 0,0 -0,1 -0,2 -0,2 -0,2 0,1

1. Torquemeter method as described above was applied for creation of Dyno Settings

2. Dyno Settings were used for coastdown on the dyno („Coast Down Data derived from Dyno Settings“)

3. Coastdown Method was applied on the track for reference (“Track Coast Down Data“)

4. Comparison of Total Resistance („calc. Force“) and coastdown times (“time“)

�� No significant difference found between the two methods!

To

tal R

esis

tan

ce

[N

]ROAD LOAD COMPARISON C/D MATCH VS. TORQUEMETER METHOD (2)


�� No significant difference found between the two methods!

200

300

400

500

600

700

800

900

20 30 40 50 60 70 80 90 100 110 120

Datenreihen1

Datenreihen2

Torquemeter

CoastDown

Speed [km/h]

measurement of running resistance by …€¦ · measurement of running resistance...

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