Feed-back approach on RLD Implementation options for feed-back approach on road load determination Iddo Riemersma – Transport & Environment EU-WLTP meeting 15 October 2012 - Brussels
Problem description Customer expectation: Realistic fuel consumption figures Required: Test procedure aiming at representative conditions for production vehicles (cycle, road load, temperature etc.) Road load not tested on production vehicle but on a pre-production vehicle, at a special test track and under ideal conditions ‘Flexibilities’ in current ISO 10521 road load test procedure: this offsets the homologation test results
Justification data TU Graz measured 9 to 24% higher CO2 emissions compared to TA value on 6 production vehicles by applying actual measured road load. T&E road load study showed on average 11% higher CO2 due to non-representative road load VTT measured 28% difference between reported and measured CO2, using actual road-load factors
Different approaches Feed forward approach Feed back approach Requirements Requirements Coast down test vehicle Road load data Production vehicle Requirements Requirements Requirements Requirements Coast down test vehicle Road load data Production vehicle Road load data
Objectives WLTP More representative test cycle and test procedure, leading to representative fuel consumption/CO2 emissions Level playing field for manufacturers Closing the gap between actual and homologation road-load helps to achieve these objectives Only way to close the gap is to check road-load of production vehicles (feed-back approach) All subsequent testing will be based on realistic road-load
Options for feed-back approach Check on paper Verify road-load relevant components/settings of production vehicles Check by measurement Verify actual road-load on a run-in production vehicle
Check on paper Easy to implement, e.g. in CoP Cost-effective solution, little administrative burden Simple verification procedure, no extra tolerances BUT: No guarantee on a representative road-load Tight vehicle requirements and tolerances needed
Check by measurement Best guarantee on a representative road-load Implementation via ISC or independent in-use verification Limited vehicle requirements and tolerances needed BUT: Extra tolerance range needed for production variance (and if applicable: user influences) Practical difficulties / extra costs
Implementation details Sample size Should be balanced against added costs Based on road-load consistency between vehicles Related to sanctioning measures Sample timing/frequency Better towards start of production Allow sufficient run-in time
Implementation details Tolerance Road-load variation due to production variance, user influences, test conditions, test-to-test variation Balanced tolerance: not too wide, not too narrow Alternative: manufacturer declared road load New or in-use production vehicle New vehicle: more repeatable result In-use vehicle: more representative result
Implementation details Embedded or alongside legislation Easy option: add to existing requirements (CoP or ISC) Objective option: independent verification programme Execution of verification Manufacturer (easy, but possibly unrealistic road-load) Technical Service / Type-approval authority Independent test house (objective road-load, but more difficult to organise)
Recommendations Road-load verification by measurements Testing of in-use vehicles Verification testing at independent test houses 3 to 5 vehicles per vehicle family (or family group) Manufacturer declared road-load (not to exceed) Road load verification separated from type-approval Obligation for road-load verification laid down in EU legislation (with execution and sanctioning details)
Next steps Discussion is needed on: The necessity of a feed-back approach for road-load How to establish a feed-back loop (options) Implementation details and their relations How to embed the feed-back approach into EU legislation