UN R51 Supplement 7 (03 series) · UNECE Regulation No. 51 (ECE R51) — Uniform provisions concerning the approval of motor vehicles having at least four wheels with regard to their sound emissions.
UN R51 — Supplement 7 to the 03 series of amendments
Supplement 6 → 7
- What changed
- New Annex 9 gives a measurement method for the Real Driving Additional Sound Emission Provisions (RD-ASEP). Starting from 1 July 2023 and for a period of twelve months, Annex 9 measurements must be performed during type approval of a vehicle. Compliance with Annex 9 is not mandatory for the purpose of type approval.
- New Appendix 2 to Annex 3 gives a correction for the tyre rolling sound component of pass-by sound measurements. Each valid test run must get a temperature correction and, if applicable, a test track correction according to this appendix. This applies to vehicles of category M1 and N1, and to vehicles of category M2 having a maximum authorized mass not exceeding 3,500 kg.
- New paragraph 11.13. says that Supplement 7 does not apply to existing type approvals originally granted before its date of entry into force. This applies in particular, but not limited to, Appendices 2 and 3 to Annex 3 and Annex 9.
- Why
- The Informal Working Group on Measurement Uncertainties (IWG MU) prepared its texts to introduce measures to reduce variability.
- IWG MU identified the temperature behaviour of the tyre rolling sound component as a contributor to the measurement uncertainty of pass-by noise tests.
- RD-ASEP is introduced in parallel with Annex 7 for twelve months to determine the practicability of a new requirement including its limit values.
Q1What changed741 changes
Definition of maximum net power Pn (para. 2.8.)
Paragraph 2.8. defines “Maximum net power, Pn” as the engine power available for propulsion expressed in kW and measured dependent on the drive train concepts. New paragraph 2.8.1. covers vehicles with combustion engine(s) only (ICE). Paragraph 2.8.2. covers BEV or FCEV that have only one propulsion energy converter. Paragraph 2.8.3. covers HEV, or pure electric vehicles that have more than one propulsion energy converter. Before this supplement, the term was “Rated maximum net power”, and paragraph 2.8.1. gave a rule for two or more sources of propulsive power.
Ambient conditions, vehicle selection and preparation of the vehicle (Annex 3, paras. 1.4. to 2.2.)
Paragraph 2.1.3. of Annex 3 now has separate subparagraphs for the ambient condition indoor and the ambient condition outdoor. Outdoor tests now also need a test surface temperature within the range from 5 °C to 60 °C. Ambient temperature may of necessity be restricted to a narrower range so that all key vehicle functionalities are enabled according to manufacturer's specifications. New subparagraphs on vehicle preparation before testing cover the battery state of charge, active sound systems, tyres and the suspension trim level. Before testing, tyres must be conditioned (broken-in), representative to about 100 km of normal on-road operation. Under Annex 6, paragraph 2.1., a manufacturer may use a simplified tyre conditioning according to the vehicle manufacturer's specification.
Microphones, gear selection and maximum engine speed nMAX (Annex 3, paras. 3.1.1. to 3.1.2.1.6.)
For outdoor testing, the microphones must be located on both sides of the pathway. For indoor testing, microphones on one side of the roller bench can be used. Where the gear selection conditions referred to the rated engine speed, they now refer to the maximum engine speed nMAX. New text gives the formula for nMAX: nMAX = 1.56 × PMR−0.227 × S, but not more than 80% of S. Paragraph 3.1.2.1.4.2. covers vehicles with automatic transmission, adaptive transmissions and CVTs tested with non-locked gear ratios. For these vehicles, the manufacturer must, if possible, take measures to avoid an engine speed higher than nMAX.
Calculation of results with temperature and test track correction (Annex 3, para. 3.1.3., and Appendices 2 and 3)
For outdoor tests, left and right must be measured simultaneously; before, they could be measured simultaneously or sequentially. New Appendix 2 to Annex 3 gives the correction for the tyre rolling sound component of pass-by sound measurements. New Appendix 3 to Annex 3 gives a coast-by test method for measuring tyre-rolling sound emission. New paragraph 3.4.2. says that independent tyre rolling sound reference measurements are not mandatory, but at the vehicle manufacturer's option and responsibility. New paragraph 12.2. lets Contracting Parties applying this Regulation designate laboratories of vehicle manufacturers as approved test laboratories. This applies to tyre rolling sound measurements according to paragraph 3.4.2.
Real Driving Additional Sound Emission Provisions (RD-ASEP) (para. 5.1.1. and new Annex 9)
New Annex 9 gives a measurement method to evaluate compliance with the Real Driving Additional Sound Emission Provisions (RD-ASEP). RD-ASEP applies only to M1 and N1 vehicles with an ICE for propulsion or with another propulsion technology fitted with an exterior sound enhancement system. Under paragraph 5.1.1., Annex 9 measurements must be performed during type approval from 1 July 2023 for a period of twelve months. Compliance with Annex 9 is not mandatory for the purpose of type approval. RD-ASEP tests are not mandatory for vehicles with PMR not exceeding 60, and do not apply to tests for the extension of existing approvals. Annex 9 tests done in the course of type approval must be witnessed by the Authority present during the tests.
Transitional provisions (paras. 11.6., 11.8. and 11.13.)
The date in paragraph 11.6. changes from 30 June 2022 to 30 June 2025. Until then, serial hybrid vehicles whose combustion engine has no mechanical coupling to the power train are excluded from paragraph 6.2.3. The date in paragraph 11.8. changes from 30 June 2022 to 31 December 2023. Until then, paragraph 11.8. covers vehicle types of category N1 or M1 derived from N1 that meet all the listed specifications. For these, the paragraph 6.2.2. limits of N1 vehicle types having a technically permissible maximum laden mass above 2.5 tons apply. New paragraph 11.13. says that Supplement 7 does not apply to existing type approvals originally granted before its date of entry into force.
Manipulation, references and footnotes (paras. 6.1. and 6.2.3.)
The title of paragraph 6.1. is now “General specifications for durability and against manipulation”. Paragraph 6.1.2. adds the words “and against manipulation” at the end of the requirement for the sound reduction system. In paragraph 6.2.3., the ASEP control range is now “defined in paragraph 2.3. of Annex 7”, in place of paragraph 3.3. The footnotes that refer to the Consolidated Resolution on the Construction of Vehicles (R.E.3) now refer to document ECE/TRANS/WP.29/78/Rev.6.
Q2Why it changed
- Proposed by
- Informal Working Group on Measurement Uncertainties; Informal Working Group on Additional Sound Emission Provisions; Experts of China (paragraph 11.8.); France, Germany, Norway and OICA (paragraph 11.13.)
- Working party
- GRBP, 74th session (September 2021) and 75th session (February 2022)
Reasons
IWG MU prepared the text to introduce measures to reduce variability. The chapter on ambient conditions (2.1.3.) was completely restructured for more clarity and to differentiate between indoor and outdoor testing. A new road surface temperature recording requirement is to limit its variability within the range from 5 °C to 60 °C. Proper tyre conditioning is necessary for achieving representative, repeatable and reproducible test results. IWG MU identified the temperature behaviour of the tyre rolling sound component as a contributor to the measurement uncertainty of pass-by noise tests. The group worked out a temperature correction adapted to the requirements of UN Regulation No. 51.
Sources (6)
“The text below has been prepared by the experts of the Informal Working Group on Measurement Uncertainties (IWG MU) in order to introduce measures to reduce variability.”
“Chapter 2.1.3. for ambient conditions has been completely restructured for more clarity and to differentiate between indoor and outdoor testing.”
“A new requirement for road surface temperature recording has been introduced to limit the variability of the road surface temperature within the range from 5 °C to 60 °C.”
“Proper tyre conditioning has been introduced, because this is necessary for achieving representative, repeatable and reproducible test results”
“The Informal Working Group on Measurement Uncertainties (IWG MU) identified the temperature behaviour of tyre rolling sound component as a contributor to the measurement uncertainty of pass-by noise tests.”
“the group worked out a temperature correction, which is adapted to the requirements of UN Regulation No. 51.”
Current noise reduction technologies in M1 and N1 vehicles, for example flap silencer systems and sound actuators, allow free shaping of the vehicle sound emissions. The current test criteria of Annex 7 only test the sound emissions under the full load in some transmission ratios. With RD-ASEP, the sound emissions of all load conditions are to be assessed in the future. RD-ASEP is introduced in parallel with Annex 7 for twelve months to determine the practicability of a new requirement including its limit values. For granting type approval, only the requirements of Annex 3 and Annex 7 continue to be decisive.
Sources (5)
“The technologies currently used in systems for noise reduction in motor vehicles of classes M1 and N1 (e.g. flap silencer systems, sound actuators) allow free shaping of the vehicle sound emissions.”
“The current test criteria of Annex 7 only test the sound emissions under the full load in some transmission ratios.”
“With the introduction of RD-ASEP, the sound emissions of all load conditions shall be assessed in the future.”
“In order to determine the practicability of a new requirement including its limit values, the requirements of RD-ASEP will be introduced in parallel with the requirements of Annex 7 for a period of twelve months”
“For granting type approval, only the requirements of Annex 3 and Annex 7 continue to be decisive.”
The Informal Working Group on Additional Sound Emission Provisions (IWG ASEP) prepared the text to improve the current wording for better clarification. For better clarity, the definition of “Maximum net power, Pn” has been adjusted to each propulsion technology (ICE, BEV, HEV, FCEV). The symbol nMAX was added for simplification in Annex 3. Clarification was added on two microphones on the test track in line PP’, instead of one microphone as allowed in the past. Both sides are then measured in one run, and the proposal says that this change will increase accuracy.
Sources (5)
“The text reproduced below was prepared by the experts from the Informal Working Group on Additional Sound Emission Provisions (IWG ASEP) in order to improve the current wording for better clarification.”
“for better clarity, the definition has been adjusted to each propulsion technology (ICE, BEV, HEV, FCEV).”
“the symbol nMAX for maximum engine rotational speed permitted for M1, N1, and M2 less than 3500 kg used for simplification in Annex 3 as 80 per cent of S has been added.”
“clarification has been added on the two microphones to be installed on the test track in line PP’ instead of one microphone as allowed in the past, for measurements in one run of both sides left/right.”
“This change will increase accuracy.”
The expert from China proposed to extend the transitional period in paragraph 11.8. The reason was the difficulties of microvans and microtrucks available at the national market in meeting the noise limits. GRBP agreed to extend the transitional period until the end of 2023.
Sources (3)
“The expert from China proposed to extend the transitional period in paragraph 11.8. of the 03 series of amendments to UN Regulation No. 51”
“due to the difficulties in meeting the noise limits by microvans and microtrucks available at the national market”
“GRBP agreed to extend the transitional period until the end of 2023”
Proposer's reason (informal document GRBP-75-36)
Paragraph 11.6. postpones by 3 additional years the application date for serial hybrid vehicles whose combustion engine has no mechanical coupling to the power train. Annex 7 ASEP cannot be applied to these vehicles because there are no valid data according to the Annex 7 test. An extension is needed until the expected date to introduce RD-ASEP.
Submitted by Informal Working Group on Additional Sound Emission Provisions. Working party adoption: ECE/TRANS/WP.29/GRBP/73, para. 4.
Sources (3)
“Paragraph 11.6. has been amended to postpone by 3 additional years the application date for vehicles with a serial hybrid drive train which have a combustion engine with no mechanical coupling to the power train.”
“are excluded from the requirements of paragraph 6.2.3. because current ASEP in Annex7 cannot be applied to those vehicles due to no valid data according to Annex7 test.”
“Therefore extension of traditional provision is needed until expected date to introduce RD-ASEP.”
Document trail
- 2021-07ProposalECE/TRANS/WP.29/GRBP/2021/22IWG MU proposal on ambient conditions, vehicle selection and preparation
- —Working party adoptsECE/TRANS/WP.29/GRBP/72Session report, para. 5
- 2021-11ProposalECE/TRANS/WP.29/GRBP/2022/3IWG ASEP proposal to improve the current wording
- 2021-11ProposalECE/TRANS/WP.29/GRBP/2022/8IWG MU proposal on temperature and test track compensation
- 2021-11ProposalECE/TRANS/WP.29/GRBP/2022/4IWG ASEP proposal to introduce RD-ASEP
- —Amended in sessionGRBP-75-36Amendment to ECE/TRANS/WP.29/GRBP/2022/3
- —Amended in sessionGRBP-75-37Amendment to ECE/TRANS/WP.29/GRBP/2022/4
- —ProposalGRBP-75-40Proposal from the experts of China to extend the transitional period in paragraph 11.8.
- —Working party adoptsECE/TRANS/WP.29/GRBP/73Session report, paras. 4 to 9
- 2022-04Sent to WP.29ECE/TRANS/WP.29/2022/84Text that GRBP sent to WP.29 and AC.1
- —Amended in sessionWP.29-187-07Corrigendum at WP.29 that adds paragraph 11.13.
- 2022-06WP.29 adoptsECE/TRANS/WP.29/1166Adopted at the 187th session (session report, para. 182)
- 2023-01-04In forceC.N.474.2022.TREATIES-XI.B.16.51UN depositary notification
Q3Who is affected
Vehicle manufacturer
- Check the maximum net power Pn of each vehicle type against paragraphs 2.8.1. to 2.8.3. for its propulsion type.
- For outdoor tests, make sure that the test surface temperature is within the range from 5 °C to 60 °C.
- Make sure that the test tyres are conditioned (broken-in) and warmed up as paragraph 2.2.3.4.2. of Annex 3 requires.
- Plan RD-ASEP measurements for type approvals from 1 July 2023 for twelve months, where paragraph 5.1.1. makes them mandatory.
- Check the dates 30 June 2025 (para. 11.6.) and 31 December 2023 (para. 11.8.) for vehicle types that use them.
Component supplier
- If you supply active sound devices, make sure that they operate as foreseen by the vehicle manufacturer during the measurements.
- If you supply exterior sound enhancement systems, be ready to support the RD-ASEP tests of Annex 9.
- If you supply sound reduction systems, check their design against the words “and against manipulation” added to paragraph 6.1.2.
Technical service / Approval authority
- For M1, N1 and M2 (up to 3,500 kg maximum authorized mass) vehicles, apply Annex 3, Appendix 2 corrections.
- For outdoor tests, measure left and right simultaneously with microphones on both sides of the pathway.
- Use the test results of Annex 3 within Annex 7 without any temperature correction.
- Be ready for the Authority to be present at the Annex 9 tests done in the course of type approval.
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ⓘ This report gives advice only. It is not legal or type-approval advice.