UN R51 Supplement 8 (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 8 to the 03 series of amendments
Supplement 7 → 8
- What changed
- The surface of the test track and the dimensions of the test site must be in accordance with ISO 10844:2021. Until five years from the entry into force of Supplement 8, ISO 10844:2014 must also be accepted for all approvals granted under this Regulation.
- Annex 3, paragraph 3.1.3.4.1.2. adds a case where Lwot,rep is less than Lcrs,rep. In this case, kP = 1 and the final result Lurban is the result of the cruise test. Under paragraph 3.1.2.1.3., kP is used for category M1, N1 and M2 < 3,500 kg technically permissible maximum laden mass.
- Under new paragraph 11.14., Supplement 8 does not apply to existing type approvals originally granted before the date of entry into force of Supplement 7.
- Why
- For battery electric vehicles (BEVs), the sound in cruising may be higher than during acceleration, and then the current temperature correction will be inaccurate.
- ISO updated the ISO 10844 standard to reduce track-to-track variability.
- In Supplement 7, the content of paragraph 3.1.3.1. was moved to paragraph 3.1.3.4.1.2. without any change, so the references to it needed the new number.
Q1What changed30 changes
Test track to ISO 10844:2021 (Annex 3, para. 2.1.1., and Annex 3, Appendix 3, para. 5.1.4.1.)
The surface of the test track and the dimensions of the test site must be in accordance with ISO 10844:2021. Before this supplement, they had to be in accordance with ISO 10844:2014. Paragraph 5.1.4.1. of Annex 3, Appendix 3 now asks for the date of track certification to ISO 10844: 2014/2021. A new footnote says to delete what does not apply according to the transitional provisions in this Regulation.
Transitional provisions for Supplement 8 (paras. 11.14. and 11.15.)
Under new paragraph 11.14., Supplement 8 does not apply to existing type approvals originally granted before the date of entry into force of Supplement 7. New paragraph 11.15. says that ISO 10844:2021 must be accepted for all approvals granted under this Regulation from the entry into force of Supplement 8. Until five years from that date, ISO 10844:2014 must also be accepted for all approvals granted under this Regulation.
Final result Lurban when Lwot,rep is less than Lcrs,rep (Annex 3, para. 3.1.3.4.1.2.)
New text in Annex 3, paragraph 3.1.3.4.1.2. says that, in cases where Lwot,rep is less than Lcrs,rep, kP = 1. In these cases, the final result Lurban is the result of the cruise test (Lurban = Lcrs,rep). Under paragraph 3.1.2.1.3., kP is used for category M1, N1 and M2 < 3,500 kg technically permissible maximum laden mass. Paragraph 3.1.3.4.1.2. now says that the final result is calculated by combining Lwot rep and Lcrs rep, in place of Lacc rep and Lcrs rep.
Tyre component when LTR,wot,j,ϑwot is greater than Lwot,j (Annex 3, Appendix 2, para. 3.3.4.)
Annex 3, Appendix 2, paragraph 3.3.4. extracts the power train component LPT,wot,j from the reported acceleration test Lwot,j. In case that LTR,wot,j,ϑwot is greater than Lwot,j, item (a) gives the formula for the power train component LPT,wot,j. New item (b) says that the tyre component LTR,wot,j,ϑref is determined by LTR,wot,j,ϑref = LTR,ϑref,vTR,ref.
Maximum net power Pn in the power to mass ratio index (Annex 3, para. 3.1.2.1.1.)
In the PMR formula, Pn is now defined according to paragraph 2.8. of the main body. The text on two or more sources of propulsive power is deleted. That text applied if two or more sources of propulsive power operate at the conditions of test of paragraph 3.1.2.1. It said that the total engine net power, Pn, had to be the arithmetic sum of parallel propulsive engines on the vehicle.
References to paragraph 3.1.3.4.1.2. in the table of symbols and Annex 3, para. 3.1.2.1.3.
In the table of symbols and in Annex 3, paragraph 3.1.2.1.3., the references to paragraph 3.1.3.1. become references to paragraph 3.1.3.4.1.2. In the table of symbols, “Lcrs i” and “Lwot i” now read “Lcrs (i)” and “Lwot (i)”.
Flowcharts in Figures 4a to 4f (Annex 3, Appendix 1)
Figures 4a to 4f in Annex 3, Appendix 1 are amended. In Figures 4a to 4e, the steps that compute kP refer to paragraph 3.1.3.4.1.2.
Q2Why it changed
- Proposed by
- Informal Working Group on Measurement Uncertainties; International Organization for Standardization (ISO 10844:2021); experts from the Informal Working Group on Measurement Uncertainties, the Informal Working Group on Additional Sound Emission Provisions and ISO (corrections)
- Working party
- GRBP, 76th session (September 2022)
Reasons
The temperature correction in Supplement 7 is based on the sound behaviour of internal combustion engine (ICE) vehicles. For battery electric vehicles (BEVs), the dominant source is the tyre road noise, so the sound in cruising may be higher than during acceleration. In this case, the current temperature correction will be inaccurate and cause an additional burden to the BEVs. The proposal says that Supplement 8 will reduce this additional burden regarding the introduction of stage 3 limits.
Sources (4)
“The temperature correction in Supplement 7 is based on the sound behavior of internal combustion engine (ICE) vehicles.”
“For battery electric vehicles (BEVs) the dominant source is the tyre road noise. For this reason, the sound emission in cruising may be higher than during acceleration.”
“In this case the current temperature correction will be inaccurate and cause an additional burden to the BEVs.”
“the proposed Supplement 8 will reduce this additional burden to BEVs regarding the introduction of stage 3 limits”
A reported value of Lurban may be smaller than Lcrs in this special case. To avoid confusion, Lurban is set to Lcrs. The main burden is caused by an improper speed correction of the tyre rolling sound LTR,wot,j,ϑ_ref. For this reason, the speed correction according to Annex 3, Appendix 2, paragraph 3.3.1. is not applied in this special case.
Sources (2)
“To avoid confusion due to a reported value of Lurban, which may be smaller than Lcrs in this special case, Lurban is set to Lcrs”
“Since the main burden is caused by an improper speed correction of the tyre rolling sound LTR,wot,j,ϑ_ref , the speed correction according to Annex 3, Appendix 2, paragraph 3.3.1. is not applied in this special case.”
With Supplement 7, the definition of “Maximum net power, Pn” in paragraph 2.8. was adjusted for better clarity. The proposal amends the text in the definition of the power to mass ratio index (PMR) to align it with this adjustment.
Sources (2)
“With Supplement 7, the definition of "Maximum net power, Pn" in paragraph 2.8. has been adjusted for better clarity.”
“It is therefore proposed to amend the text in the definition of power to mass ratio index (PMR), in order to align it with the adjustment in Supplement 7.”
ISO updated the ISO 10844 standard to improve clarity. The primary objective is to reduce track-to-track variability caused by differing interpretations and implementations of the technical requirements.
Source
“ISO has updated the 10844 standard to improve clarity. The primary objective is to reduce track-to-track variability caused by differing interpretations and implementations of the technical requirements.”
The content of paragraph 3.1.3.1. was moved to paragraph 3.1.3.4.1.2. without any change in Supplement 7. The references to it in the table of symbols, in paragraph 3.1.2.1.3. and in the figures needed the new number 3.1.3.4.1.2.
Sources (4)
“The content of paragraph 3.1.3.1. was moved to paragraph 3.1.3.4.1.2. without any change when the measurement uncertainties and the real driving additional sound emission provisions (RD-ASEP) were introduced in Supplement 7.”
“In the table of symbols, the references to this paragraph 3.1.3.1. need to be renumbered to 3.1.3.4.1.2., accordingly.”
“In paragraph 3.1.2.1.3., the reference to this paragraph 3.1.3.1. needs to be renumbered to 3.1.3.4.1.2., accordingly.”
“In the figures, references to this paragraph 3.1.3.1. need to be renumbered to 3.1.3.4.1.2., accordingly.”
Document trail
- 2022-06ProposalECE/TRANS/WP.29/GRBP/2022/13Proposal by ISO for ISO 10844:2021
- 2022-06ProposalECE/TRANS/WP.29/GRBP/2022/16Proposal by the Informal Working Group on Measurement Uncertainties
- —Amended in sessionGRBP-76-09Amendment to GRBP/2022/16 by the experts of IWG MU
- —Working party adoptsECE/TRANS/WP.29/GRBP/74Session report, paras. 3 and 6
- 2022-11ProposalECE/TRANS/WP.29/GRBP/2023/12Proposal for corrections to the 03 series of amendments
- 2022-12Sent to WP.29ECE/TRANS/WP.29/2023/2Text that GRBP sent to WP.29 and AC.1
- 2023-03WP.29 adoptsECE/TRANS/WP.29/1171Adopted at the 189th session (session report, para. 127)
- 2023-09-24In forceC.N.409.2023.TREATIES-XI.B.16.51UN depositary notification
Q3Who is affected
Vehicle manufacturer
- Plan approvals that use an ISO 10844:2014 test track within five years from the entry into force of Supplement 8.
- Check your Lurban results under Annex 3, paragraph 3.1.3.4.1.2. for vehicles where Lwot,rep is less than Lcrs,rep.
- Check that the Pn used for the PMR follows the definition in paragraph 2.8. of the main body.
Component supplier
- No direct action for this role.
Technical service / Approval authority
- Check the test track and test site against ISO 10844:2021, or ISO 10844:2014 within the period of paragraph 11.15.
- Update your Lurban calculation under Annex 3, paragraph 3.1.3.4.1.2. for the cases where Lwot,rep is less than Lcrs,rep.
- Update how you determine the tyre component LTR,wot,j,ϑref when LTR,wot,j,ϑwot is greater than Lwot,j.
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ⓘ This report gives advice only. It is not legal or type-approval advice.