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NEDC consumption measurement: a test drive on the conveyor belt

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NEDC consumption measurement
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E What matters is what comes out at the back - this quote from the former Chancellor also fits perfectly The topic of consumption measurement. Because for the determination of the manufacturer's information according to the EU standard, it is not the de facto amount of fuel used that is measured, but the amount of pollutants emitted, or more precisely: that of the hydrocarbon-containing emission products, i.e. HC, CO and CO2. From these, the fuel volume can be determined using a handy formula. Before that happens, however, a large number of requirements for test preparation and execution have to be met - the set of rules comprises 56 pages. If you want to read: ECE standard R83, appendix four.

Michael Angel does not need that - he is a Daimler specialist for emissions certification worldwide (except North America) and knows the regulations by heart. Whether this is a curse or a blessing is not an issue for him, nor is the question of possible loopholes: 'The conditions for the measurement cycle are so precisely specified that there is hardly any leeway for implementation. But that is definitely in our sense - because for As a manufacturer, it is important to us that reproducibility is guaranteed all over the world. '

Each trip on the roll costs around 1,700 Euro

Daimler goes to great lengths to meet the requirements of the various international certification processes. At the Sindelfingen location, the company has an air-conditioned test building with seven roller dynamometers and a pallet warehouse for up to 80 cars, in which the test subjects are conditioned according to the respective specifications. Up to 100 driving cycle tests take place here every day, around 30,000 annually. Not a cheap undertaking: Each trip on the reel costs the group around 1,700 euros.

Test bench E3 is reserved for us today, accompanied by Michael Angel and production engineer Alexander Sauer, we are allowed to test according to the New European Driving Cycle ( NEDC). The red A 180 CDI stands with the driven front axle on the test stand roller and is fixed at the front and rear. The exhaust gases are extracted directly from the tailpipes, mixed with the ambient air in a defined ratio and finally collected in low-reaction plastic bags for evaluation.

Switching points are precisely defined in NEDC measurements

The challenge for the driver is now the one given on the monitorKeep to the speed exactly - otherwise the measurement is invalid. In cars with manual gearshift, the switching points are also precisely defined - not always to the benefit of the test person, says test bench manager Reiner Hils, who sits at the wheel of the A 180 CDI: 'In models with a start-stop function, you lose a few seconds of engine downtime by engaging the clutch early. ' Air conditioning and other consumers have to pause during the measurement - the EU wants it that way. The cycle ride itself is unspectacular, we only reach higher speeds in the overland section and the front end vibrates slightly on the roller. After almost 20 minutes everything is over, the program stops.

And what does the test future look like? 'Together with the other manufacturers and authorities, we are working on a globally standardized test cycle,' says Michael Angel. 'Driving profiles determined in road traffic flow into this,' promises the expert a little more practical. The test bench values ​​can already be traced on the road, confirms Angel: 'Those who drive according to cycle specifications can achieve the standard values.'

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