Technical feasibility of different regulatory OBD threshold limits (OTL) for Euro 6 (LD) vehicles

Transcription

1 Technical feasibility of Euro 6 OBD threshold limits (OTL) 1 Technical feasibility of different regulatory OBD threshold limits (OTL) for Euro 6 (LD) vehicles Presentation of the results of the study 24 September 2014 Prof. Zissis Samaras (LAT), Savas Geivanidis (LAT), Robin Vermeulen (TNO), Willar Vonk (TNO), Andy Noble (Ricardo), Jon Andersson (Ricardo), Hector Sindano (Ricardo)

2 Technical feasibility of Euro 6 OBD threshold limits (OTL) 2 Contents Introduction, project overview Worldwide OBD requirements, certification procedures, test methods and technologies (WP100) Relation between EU and worldwide OBD requirements (WP200) Particle Matter (PM) emissions Nitrogen Oxides (NOx) emissions Summary and conclusions

3 Technical feasibility of Euro 6 OBD threshold limits (OTL) 3 Introduction, project overview Worldwide OBD requirements, certification procedures, test methods and technologies (WP100) Relation between EU and worldwide OBD requirements (WP200) Particle Matter (PM) emissions Nitrogen Oxides (NOx) emissions Summary and conclusions

4 Technical feasibility of Euro 6 OBD threshold limits (OTL) 4 European legislation Regulation 459/2012/EC introduces "final" Euro 6 OBD threshold limits (OTLs), applicable to passenger cars as from 1 September 2017 (see values below). CO [mg/km] NMHC [mg/km] NOx [mg/km] PM [mg/km] Gasoline Diesel Gasoline Diesel Gasoline Diesel Gasoline Diesel Preliminary (from September 2014/15) Final (from September 2017/18) The Regulation contains a clause that the European Commission should assess the "technical feasibility" of these OTLs by 1 st September 2014 and suggest regulatory amendments if necessary. This clause was introduced in order to address concerns raised by some Member States having to do with the effectiveness of soot sensors to meet the PM OTL of 12 mg/km and some concerns about the NOx OTL of 140 mg/km.

5 Technical feasibility of Euro 6 OBD threshold limits (OTL) 5 Project objective The current project provides an assessment of the technical feasibility of the Euro 6 OBD threshold limits as required by the Commission Regulation (EU) No 459/2013. In view of the fact that vehicles with soot and NOx sensors are already certified in the USA is a clear indication that soot and NOx sensor technology for OBD purposes is "technically feasible. Therefore the required assessment had to take this fact into account and assess any issues that may impact introduction in the EU market.

6 Technical feasibility of Euro 6 OBD threshold limits (OTL) 6 Project overview Subject: support the technical feasibility assessment of "Final Euro 6 OTLs" for PM and NOx, as defined in Regulation (EC) 692/2008 as amended by Regulation (EC) 459/2012 Work Package 100: Investigation of worldwide OBD requirements, certification procedures, test methods and technologies introduced by OEMs on latest vehicle models. Work Package 200: Evaluation of existing data to assess the relation between EU and worldwide OBD requirements, certification procedures and vehicle technologies based on vehicle, engine and aftertreatment system modelling. Work Package 300: Reporting, results dissemination, ad-hoc support to the Commission and project Coordination.

7 Technical feasibility of Euro 6 OBD threshold limits (OTL) 7 Introduction, project overview Worldwide OBD requirements, certification procedures, test methods and technologies (WP100) Relation between EU and worldwide OBD requirements (WP200) Particle Matter (PM) emissions Nitrogen Oxides (NOx) emissions Summary and conclusions

8 Technical feasibility of Euro 6 OBD threshold limits (OTL) 8 European vs. US OBD requirements (1 of 3) CARB OBD-II (Ref.[1]) Ref Euro OBD (Ref.[2]) Ref OBD System must operate without maintenance for actual [1] OBD System must operate over the entire life of the [2] life of vehicle (d) (1) vehicle but may show degraded monitoring performance due to ageing 3.1 Monitoring conditions must be encountered in normal urban use, and must occur during the FTP cycle or Unified cycle Demonstration Test: Not witnessed by ARB Use durability test vehicle, or a representative high mileage vehicle, or vehicle aged to end of full useful life using ARB-approved durability procedure Pre-conditioning: FTP, SET, or Unified Cycle (+ 1 cycle identical to the initial preconditioning cycle, or a Federal Highway Fuel Economy Driving Cycle if required) Manufacturer may not require test vehicle to be cold soaked prior to conducting preconditioning cycles [1] (d) (3) [1] (h) (2.3) [1] (h) (5.1) Monitoring conditions must be encountered in normal use, and must occur during NEDC cycle. Demonstration Test: Witnessed by cert authority Use durability test engine or suitably aged and representative vehicle Pre-conditioning: Part 1 and 2 NEDC (+ 2 Part 2 s if required) Alternative pre-condition cycle may be allowed if requested [1] CARB. Section Title 13, California Code of Regulations (13 CCR ) as filed with the Secretary of State on July 31, 2013, [2] COMMISSION REGULATION (EU) No 459/2012 of 29 May 2012 amending Regulation (EC) No 715/2007 of the European Parliament and of the Council and Commission Regulation (EC) No 692/2008 as regards emissions from light passenger and commercial vehicles (Euro 6) [2] 3.2 [2] [2] App

9 Technical feasibility of Euro 6 OBD threshold limits (OTL) 9 European vs. US OBD requirements (2 of 3) CARB OBD-II (Ref.[1]) Ref Euro OBD (Ref.[2]) Ref Test Sequence: [1] Test Sequence: [2] (h) App.1 (5.2) (2) 1) Install faulty component (at the OTL) on the test vehicle (or simulated fault) 2) Carry out preconditioning 3) If required, a cold soak may be performed at this stage 4) Operate test vehicle over the applicable cycle to allow initial detection of the malfunction 5) Operate test vehicle over applicable emission test Evaluation Protocol: MIL must illuminate before the end of the first engine start portion of the exhaust emission test If MIL illuminates prior to emissions exceeding applicable OTL, no further demonstration is required. If MIL does not illuminate either the OTL or the OBD II system is not acceptable. If MIL first illuminates after emissions exceed the OTL, the test vehicle shall be retested with the component adjusted so that the MIL will illuminate before emissions exceed the OTL. [1] (h) (6) 1) Install faulty component (at the OTL) on the test vehicle (or simulated fault) 2) Carry out preconditioning 3) Operate test vehicle with a simulated malfunction over NEDC test cycle and measure emissions (Manufacturer may request that monitoring take place outside the NEDC test cycle) Evaluation Protocol: MIL shall illuminate upon detection of the tested component when measured over the NEDC test cycle. Such defective components shall not cause emissions to exceed the OTL by more than 20%. [2] & App.1

10 Technical feasibility of Euro 6 OBD threshold limits (OTL) 10 European vs. US OBD requirements (3 of 3) CARB OBD-II (Ref.[1]) Ref Euro OBD (Ref.[2]) Ref Confirmatory Testing: [1] Confirmatory Testing: N/A (h) (7) CARB may within 6 months of approving the data submitted by the manufacturer, request to perform confirmatory testing to verify the emission test data submitted by the manufacturer Vehicles may be recalled for corrective action if a representative sample fails the Confirmatory Testing Deficiencies: Factors considered: Extent to which the OBD requirements are satisfied Demonstrated good-faith effort to meet the requirements in full Manufacturers are subject to fines of either $50 or $25 per deficiency per vehicle for each noncomplying system starting with the third deficiency. Total fines may not exceed $500 per vehicle. Deficiencies may not be retroactively granted after certification In Use Performance Monitoring IUMPR for PM Filter and NOx After- Treatment related monitors At least 500 miles of vehicle operation needed to increment IUPR counter for PM Filter [1] (k) [1] (d) (3.2.1) Not required as the original demonstration test is witnessed by the certification authorities Deficiencies: Factors considered: Extent to which compliance is not feasible or is unreasonable Deficiency not acceptable where there is a complete lack of monitor No fines are imposed Retrospective deficiencies are allowed In Use Performance Monitoring IUPR 0.1 for all monitors At least 800 cumulative kilometres of vehicle operation must be experienced in order to increment the IUPR counter for PM Filter [2] 4.5 [2] (7)

11 Technical feasibility of Euro 6 OBD threshold limits (OTL) 11 How US PM certification data has been compiled Certification Data from CARB Website Test Group 2014 PC/LDT _diesel_ Communication with CARB: Initial list of Vehicles Certified with PMS in the US EPA Document Index System Detailed Emissions data (PDF) Either has PMS on EO or is on CARB List Summary Spreadsheet + PDF files CARB Certified 2014MY Pass Cars with PMS.xlsx

12 Technical feasibility of Euro 6 OBD threshold limits (OTL) 12 US LDVs certified with NOx and PM Sensors Vehicle Make Model Engine Size (Litres) Vehicle Type Emission Standard OBD-II PM Emissions [g/mile] STD:0.01 g/mile OBD OTL: g/mile NOx Emissions [g/mile] STD: 0.07 g/mile OBD OTL: g/mile NOx Sensor Mercedes E250 Bin 5 ULEV 2.1 PC BluTec 4Matic 2 Partial Mercedes ML250 Bin 5 ULEV 2.1 PC BluTec 4Matic 2 Partial Mercedes GLK250 Bin 5 ULEV 2.1 LDT2 BluTec 4Matic 2 Partial Porsche Cayenne 3 LDT3 ULEV 2 Partial VW Touareg 3 LDT3 ULEV 2 Partial AUDI Q7 3 LDT4 ULEV 2 Partial AUDI A6, A7, A8, A8L, Q5 3 PC, LDT2 ULEV 2 Partial BMW 328d 2 PC Bin 5 ULEV 2 Partial BMW 535d 3 PC Bin 5 ULEV 2 Partial BMW X5 xdrive35d 3 LDT4 Bin 5 ULEV 2 Partial Mercedes ML350 Bin 5 ULEV 3 LDT4 BluTec 4Matic 2 Partial Mercedes GL350 Bin 5 ULEV 3 LDT4 BluTec 4Matic 2 Partial PM

13 Technical feasibility of Euro 6 OBD threshold limits (OTL) 13 US LDVs certified with NOx and PM Sensors (cont d) Vehicle Make GM (Chevrolet) Chrysler Model LUZ Cruze Diesel D1SC JEEP Grand Cherokee Engine Size (Litres) Vehicle Type 2 PC 3 LDT4 Volkswagen Touareg 3 LDT3 AUDI Q7 3 LDT4 AUDI A6, A7, A8, A8L, Q5 3 PC, LDT2 BMW 328d 2 PC BMW 535d 3 PC BMW X3 xdrive28d 2 LDT2 BMW 535d xdrive 3 PC BMW 740Ld xdrive 3 PC Emission Standard LEV160 LEV 3 Bin 5 ULEV 2 Bin 5 ULEV 2 Bin 5 ULEV 2 Bin 5 ULEV 2 Bin 5 ULEV 2 Bin 5 ULEV 2 Bin 5 ULEV 2 Bin 5 ULEV 2 Bin 5 ULEV 2 OBD-II PM Emissions [g/mile] STD:0.01 g/mile OBD OTL: g/mile Partial NOx Emissions [g/mile] STD: 0.07 g/mile OBD OTL: g/mile CERT: g/mile (NOx+NMHC) STD: g/mile (NOx+NMHC) NOx Sensor PM Partial Partial Partial Partial Partial Partial Partial Partial Partial

14 Technical feasibility of Euro 6 OBD threshold limits (OTL) 14 Technology to meet PM OTL Resistive soot sensors Bosch Continental Delphi Electricfil Stoneridge Resistance between electrodes decreases while soot deposits between electrodes Sensors regenerates burning soot when reaches: maximum soot deposition = maximum current = minimum resistance Measured quantity for OBD index: time between two sensor regenerations current increase slope resistance decrease slope

15 Technical feasibility of Euro 6 OBD threshold limits (OTL) 15 Technology to meet NOx OTL NOx sensor The NOx sensor is a linear real time NOx measurement instrument designed for engine control and OBD Main market supplier: NGK Accuracy Range Generation 2.0 Generation ppm ±15ppm ±10ppm > 100 ppm ±15 % ±10 %

16 Technical feasibility of Euro 6 OBD threshold limits (OTL) 16 Introduction, project overview Worldwide OBD requirements, certification procedures, test methods and technologies (WP100) Relation between EU and worldwide OBD requirements (WP200) Particle Matter (PM) emissions Nitrogen Oxides (NOx) emissions Summary and conclusions

17 Technical feasibility of Euro 6 OBD threshold limits (OTL) 17 Introduction, project overview Worldwide OBD requirements, certification procedures, test methods and technologies (WP100) Relation between EU and worldwide OBD requirements (WP200) Particle Matter (PM) emissions Nitrogen Oxides (NOx) emissions Summary and conclusions

18 Technical feasibility of Euro 6 OBD threshold limits (OTL) 18 Modelling and evaluation of PM OBD system performance

19 Technical feasibility of Euro 6 OBD threshold limits (OTL) 19 PM sensor model Available data Average sensor behavior A sensor model was created in order to simulate sensor performance over the modelled driving cycles Soot sensor model was based on tests with sensors already available in the market

20 Soot [g/s] Consortium of LAT, TUG, Ricardo and TNO Technical feasibility of Euro 6 OBD threshold limits (OTL) 20 Vehicle model - x Speed [1/min] Torque [Nm] A soot emissions model was developed using dynamic and static emission measurement data. The soot model along with the soot sensor model and a simplified DPF filtration efficiency model were integrated in IAV VeLoDyn which is a simulation tool for managing and simulating motor-vehicle powertrains.

21 Technical feasibility of Euro 6 OBD threshold limits (OTL) 21 Soot, PM model validated over NEDC with hot start (simulated vs. measured cumulative mass) Simulated cumulative emissions are in good agreement with the measured cumulative emissions over the whole duration of the NEDC cycle

22 Technical feasibility of Euro 6 OBD threshold limits (OTL) 22 Soot sensor simulation: FTP-75, DPF US OTL The soot sensor completes one full loading cycle before the middle of phase 2. This can be considered to be a successful monitoring event (detection) and would trigger MIL illumination. A second successful monitoring event is not possible before the end of phase 2 and engine stop.

23 Technical feasibility of Euro 6 OBD threshold limits (OTL) 23 Soot sensor simulation: NEDC, DPF EU OTL The soot sensor completes one full loading cycle in the middle of EUDC. This can be considered to be a successful monitoring event (detection) and would trigger MIL illumination.

24 Technical feasibility of Euro 6 OBD threshold limits (OTL) 24 Soot sensor simulation: NEDC, DPF 1.2 x EU OTL With a DPF exceeding the OTL by 20% the soot sensor is able to go through two complete loading cycles producing two successful monitoring events. This can reduce the challenge to the detection capability by providing data to the OBD algorithm for two different regions of the engine operating map.

25 Technical feasibility of Euro 6 OBD threshold limits (OTL) 25 Overview of PM simulation results The behaviour of a soot sensor was modelled over both FTP-75 and NEDC The sensor was able to produce one successful monitoring event over FTP-75 as expected since vehicles in the US are already certified as compliant to PM OTL requirements with existing soot sensor technology The same sensor was able to provide one successful monitoring event over NEDC with a malfunction simulated at OTL and two successful monitoring events over NEDC with a malfunction simulated at 20% above OTL. Therefore it was concluded that the latest vehicles certified by US EPA and CARB carry already OBD diagnostic technologies that can support the implementation of the Euro 6 PM OBD threshold limits.

26 Technical feasibility of Euro 6 OBD threshold limits (OTL) 26 Introduction, project overview Worldwide OBD requirements, certification procedures, test methods and technologies (WP100) Relation between EU and worldwide OBD requirements (WP200) Particle Matter (PM) emissions Nitrogen Oxides (NOx) emissions Summary and conclusions

27 Technical feasibility of Euro 6 OBD threshold limits (OTL) 27 Assessment of NOx OBD system behaviour Methodology: assess whether a vehicle with an SCR system optimized for certification in the US can have an EU type-approval with the same NOx aftertreatment specifications. Next step: assess the effect of the malfunction that needs to be introduced to a vehicle certified by CARB on the emissions over the EU type-approval. If the same malfunction complies with the malfunction that needs to be imposed for the EU NOx OBD type-approval (=achieve exceedance of the EU NOx OTL) then the detection of this malfunction can be considered achievable (given that the vehicle already was able to detect this malfunction over the CARB certification for the US market).

28 Technical feasibility of Euro 6 OBD threshold limits (OTL) 28 SCR system simulation - According to the initial project planning, the assessment of NOx OBD threshold limits would be based purely on modelling as it was done with PM. During the first steps of model validation it was concluded that accurate engine-out NOx modelling could not be realized in an effective way. An important piece missing for this exercise was accurate engine-out real time NOx emission data over FTP-75 to further fine tune and validate the performance of the transient NOx emission model. Therefore it was decided to perform some specific tests at LAT on the vehicle dynamometer and measure real time engine-out NOx and NO emissions over both NEDC and FTP-75.

29 Technical feasibility of Euro 6 OBD threshold limits (OTL) 29 SCR system simulation - In order to simulate function, efficiency and reagent dosing of the SCR system, the SCR modelling facility of Exothermia axisuite axicat was used. Exothermia axisuite module axicat is a multi-dimensional catalyst model for the simulation of flow-through, honeycomb catalytic converters. The supported converter types include among others SCR catalysts and any custom converter by selection from a list of 70 built-in reactions or any other user-defined reactions. Reaction kinetics are expressed by Arrhenius type expressions as follows: k = A e E RT k rate of chemical reaction A pre-exponential factor E activation energy R universal gas constant T temperature (in Kelvin)

30 Technical feasibility of Euro 6 OBD threshold limits (OTL) 30 SCR system simulation - Speed, Torque, Mass flow, Temperatures ECU data NO x out Model based Exhaust line (DOC etc.) Speed, Torque, CO, CO 2 O 2, NO, NO 2 Mass flow, Temperatures SCR supervisor Adblue injection CO, CO 2 O 2, NO, NO 2 Simulated Analyzer data Input is either Simulated or Measured CO, CO 2 O 2, NO, NO 2 Measured NH 3 NO x NO x sensor model

31 Technical feasibility of Euro 6 OBD threshold limits (OTL) 31 Simulated SCR systems Two SCR systems were simulated: Baseline system was configured with optimal catalyst size and control to reduce engine-out NOx emissions down to CARB certification limits (including optimal control of reagent injection, minimization of NH 3 slip etc.) Failed system was configured exactly as the baseline system but degradation was simulated by modifying reaction kinetics to reach emissions over FTP-75 at CARB OBD threshold limit mg/mile mg/km US certification limit (Bin 5 ULEV 2, FTP-75) US OBD threshold (FTP-75) 123 (=1.75x70) 76 EU type approval limit (Euro 6, NEDC) - 80 EU OBD threshold (Euro 6, NEDC) - 140

32 Technical feasibility of Euro 6 OBD threshold limits (OTL) 32 NOx emissions over FTP-75 (engine-out, good SCR, failed SCR) The SCR system was calibrated to achieve emissions over the FTP-75 cycle of 32 mg/km, moderately below the certification limit (70 mg/mile = 43 mg/km). SCR performance degradation was simulated to increase vehicle emissions to 77 mg/km which is at exactly the CARB OTL of 76 mg/km (= 123 mg/mile = 1.75x70 mg/mile).

33 Technical feasibility of Euro 6 OBD threshold limits (OTL) 33 NOx emissions over NEDC (engine-out, good SCR, failed SCR) When the exact same system that was calibrated for compliance with FTP-75 was simulated over NEDC, emissions were measured at 24 mg/km which is significantly lower than the Euro 6 type-approval limit (80 mg/km). The same degraded SCR that was applied to the FTP-75 case was found to lead to emissions of 149 mg/km over NEDC which is slightly over the Euro 6 OTL of 140 mg/km therefore qualifies for OBD type-approval.

34 Technical feasibility of Euro 6 OBD threshold limits (OTL) 34 Cumulative distribution of NOx of Euro 6 vehicles Source of data: VCA, UK, summer 2014 The validity of the low NOx performance of the simulated vehicle was checked with early Euro 6 vehicles. Even in this early Euro 6 vehicle sample, 7.2% of the type-approved vehicles were measured to emit 24 mg/km or less of NOx over NEDC. This means that the NOx aftertreatment of the simulated vehicle that was optimized for US certification can also be considered a normal and not an overperforming NOx aftertreatment system for EU type-approval.

35 Technical feasibility of Euro 6 OBD threshold limits (OTL) 35 Overview of NOx simulation results Therefore, the OBD system of the simulated vehicle is expected to be able to detect the SCR degradation over any driving conditions in compliance to both CARB and EU type-approval requirements. Latest vehicles certified by US EPA and CARB carry already OBD diagnostic technologies that can support the implementation of the Euro 6 NOx OTL.

36 Technical feasibility of Euro 6 OBD threshold limits (OTL) 36 Introduction, project overview Worldwide OBD requirements, certification procedures, test methods and technologies (WP100) Relation between EU and worldwide OBD requirements (WP200) Particle Matter (PM) emissions Nitrogen Oxides (NOx) emissions Summary and conclusions

37 Technical feasibility of Euro 6 OBD threshold limits (OTL) 37 Discussion (PM simulation) The performance as regards PM and NOx OBD monitoring was assessed with a view to the transferability of monitoring technologies from the latest CARB OBD requirements to Euro 6 vehicles as follows. For the assessment of PM OBD thresholds a complete model was developed including a soot sensor in order to compare the performance of a accumulative soot sensor over FTP-75 with the performance over NEDC. It was found that the accumulative soot sensor can have a similar behaviour over NEDC and can achieve at least one successful monitoring event, indicating in this case that Euro 6 PM OTL is feasible.

38 Technical feasibility of Euro 6 OBD threshold limits (OTL) 38 Discussion (NOx simulation, SCR system) For the assessment of NOx OBD thresholds a vehicle was modelled from driving dynamics to the SCR system. Simulations demonstrated that a vehicle certified against US OBD requirements can also comply with Euro 6 NOx emissions and OTL with no modifications necessary either to increase or decrease the performance of the SCR. It was concluded that NOx monitoring technology already existing in US vehicles can be equally effective for compliance to Euro 6 NOx OTL.

39 Technical feasibility of Euro 6 OBD threshold limits (OTL) 39 Discussion (further optimization for EU vehicles) It needs to be stressed that all assessments were based on a limited vehicle sample, optimized to comply with CARB regulations. US vehicle results correspond to vehicles belonging to the high engine capacity diesel engines in Europe. OBD systems designed for EU vehicles are expected to be further optimized using sensors at more advance development stage given the additional lead time to the next stage of Euro 6 OBD requirements.

40 Technical feasibility of Euro 6 OBD threshold limits (OTL) 40 Conclusions and Recommendations Despite the difference between US and EU legislation and type-approval procedures, the assessment revealed similarities in operation and OBD system performance and enabled a comparison. Based on the simulation work in this study it is concluded that existing technologies allow the implementation of OBD hardware and algorithms able to cope with the stringent Euro 6 PM and NOx OBD requirements. It is proposed to keep track of rapidly developing OBD sensing hardware and monitoring technologies, the improvement of their performance and their effects on emission in view of future regulatory steps.

41 Thank you for you attention Consortium of LAT, TUG, Ricardo and TNO Technical feasibility of Euro 6 OBD threshold limits (OTL) 41