AEROSOLS Project Insights

• Additional chassis dyno quality criteria
• Threshold pressure calculation method
• Table 5.3
• Annex C clarifications and adaptations

This document evaluates the AIP dustIN multisampling PM10 system using an ILS-3 brake on a BMW X5 tested across the WLTC cycle with brake cooling airflow at 500, 1000, and 1500 m³/h. Testing involved six tests per flowrate comprising regular runs with repetitions. Deviations between multisampler and single sampling were less than 5 percent, covered by measurement uncertainty and partly caused by different sampling positions. No significant loss impact by the dustIN multisampler was identified. A PM2.5 campaign is currently running.

Proposal to amend para. 8.2.(k) to require calculation of average drag torque over a 5 s period during constant speed phases rather than acceleration phases, amend para. 8.2.(d) to clarify brake run-out measurement procedures for drum brakes including verification measurement at final assembly, amend para. 8.2.(e) to specify assembly procedures for drum brake testing, insert para. 12.1.2.3.(c) to clarify flow measurement device calibration requirements for PM sampling, and insert para. 12.2.3.2.(c) to clarify flow measurement device calibration requirements for PN sampling, based on ECE/TRANS/WP.29/GRPE/2025/6.

Proposal to establish sampling plane diameter of 300 mm or 12" with wall thickness of up to 1.5 mm, specify sampling tunnel straight section length between 8D and 10D, require single sampling plane layout with two PN probes on top and two PM probes on bottom, allow 4-probe sampling plane with flow splitter for PN connections only, prohibit flow splitter use for PM connection, permit sampling tunnel attachment directly to enclosure outlet or to 90-degree bend after enclosure, and standardize disc brake adapter and fixture and reduce drum brake S-cam length.

PMP Task Force 5 is working on HDV Brake Dyno Layout and HDV Brake Test Cycle. A GTR proposal is planned by the end of 2025.

ILS 3 Findings and GTR 24 Updates addresses improvements to the Particle Measurement Programme. References to three-probe layout and smaller duct diameters are deleted; duct inner diameter is defined as 190–225 mm. A column defining numbers of decimals is added to Table 8.1. Bedding and emissions measurement sections shall use new parts. Temperature requirements at filter holder are clarified to remain above 15°C. Requirements on decimal places are added throughout Tables 13.1, 13.3, 13.4, 13.5, and 13.6. Table 13.6 now counts from 1 to 274. Unit notation is harmonized. Signal filtering requirements are added to Chapter 5.4. Various requests are rejected, including repositioning sampling nozzles and probes, PM₁₀ probe positioning, and OEM-declared threshold pressure values.

PM samplers must sample continuously until 10 seconds after the end of the WLTP, as particles require 10 seconds to reach the filter after the last brake event. PN calculation does not completely cover all PN of the trips’ last brake event due to time delay and smoothing during the calculation period. Based on ILS data, extending the TBF export by 5 seconds would result in maximum emission factor differences of approximately 0.35 percent, estimated below 1 percent overall influence.

Proposal to establish quality criteria for applied brake torque datasets at 250 Hz sampling rate by calculating rising criterion, maximum criterion, and stability criterion for each brake event. Rising criterion measures time to reach ninety per cent of nominal brake torque and overshoot at brake event start. Maximum criterion calculates maximum brake torque weighted by nominal specific kinetic energy. Stability criterion reports average brake torque and root mean squared error weighted by nominal specific kinetic energy. Results show variation across laboratories. Further investigation necessary for different brake types, threshold definition for failed brake events, and inclusion of method and criteria reporting in event based file.

Proposal to add quality checks for applied brake torque to GTR 24, including methods for calculating Brake Torque Rising Criterion, Brake Torque Maximum Criterion, and Brake Torque Stability Criterion based on signals with frequency of 250 Hz or faster, to be recorded in Event-Based Files and reported in summary table 13.6, and to add signal filtering requirements to chapter 5.4 specifying a second order filter with cut-off frequency between 25% and 50% of the lower sampling or recording frequency to fulfill Nyquist-Shannon sampling theorem.

Figure 12.1 shows the indicative setup of the PM sampling system with sampling plane, sampling nozzle, PM sampling probe, PM cyclonic separator, PM sampling line, PM filter holder, PM sampling filter, mass or volumetric flow measurement, pump, and flow controller. Figure 12.3 shows the indicative setup of the PN sampling and measurement system with sampling plane, sampling nozzle, PM sampling probe, flow splitter, PN particle transfer tube, PN cyclonic separator, HEPA-filtered inlet for dilution air, dilution stage, Volatile Particle Remover, Particle Number Counter with internal flow controller and mass or volumetric flow measurement, and pump.

TF5-SG2 update on GTR HD brakes test cycle development. Phases include analysis of measured brake cycles from real world data, adjustment of VECTO driver model to meet real world distributions, integration of endurance brake model, and shortening VECTO mission profiles to test cycle candidate. SG2 decided to use VECTO cycles as basis, resulting speed cycle for optimisation, and cycle without road gradients. Next steps include elaborating method to calculate torque and rpm from speed cycle, further shortening cycle to approximately 4 hours, and testing cycle to elaborate quality criterion for reproducibility. Volume flow settings on HD brake dynos require elaboration in SG1.