UN R85 Supplement 8 (00 series) · UNECE Regulation No. 85 (ECE R85) — Uniform provisions concerning the approval of internal combustion engines or electric drive trains intended for the propulsion of motor vehicles of categories M and N with regard to the measurement of the net power and the maximum 30 minutes power of electric drive trains.
UN R85 — Supplement 8 to the 00 series of amendments
Supplement 7 → 8
- What changed
- Under paragraph 5.3.1.3., the motor must run on the bench for three minutes immediately before the test, at a power equal to “either 80 per cent of the maximum 30 minutes power or 80 per cent of the maximum peak power”.
- This run is at a speed recommended by the manufacturer, “within the speed range determined in paragraph 5.3.2.2”. After the run, the power test must start “within a maximum of 1 minute”.
- Supplement 8 also amends Annex 5, paragraph 5.4.2., “Diesel engines - Factor αd”, so that its formula reads “Where αd = (fa) fm”.
- Why
- The proposal says that “80% maximum power” and “80% maximum 30 minutes power” are both technically correct methods. The most suitable method depends on the motor cooling technology.
- UK raised a concern for air-cooled motors. For these motors, a 3 minute warm-up at 80 per cent maximum power can make declared net power figures much lower than the actual power.
- The proposal says that, at some time in the evolution of the text, the formula changed from “fa to the power of fm” to “fa multiplied by fm”, and that this is incorrect.
Q1What changed2 changes
Three-minute bench run before the test (para. 5.3.1.3.)
Immediately before the test, the motor must run on the bench for three minutes at a power equal to “either 80 per cent of the maximum 30 minutes power or 80 per cent of the maximum peak power”. This run is at a speed recommended by the manufacturer, “within the speed range determined in paragraph 5.3.2.2”. After the run, the power test must start “within a maximum of 1 minute”. Before this supplement, the power for this run was “80 per cent of the maximum power at the speed recommended by the manufacturer”.
Power correction factor for diesel engines (Annex 5, para. 5.4.2.)
Supplement 8 amends Annex 5, paragraph 5.4.2., “Diesel engines - Factor αd”, so that its formula reads “Where αd = (fa) fm”. The paragraph gives the power correction factor (αd) for diesel engines at constant fuel rate.
Q2Why it changed
- Proposed by
- Expert from the International Organization of Motor Vehicle Manufacturers
- Working party
- GRPE, 76th session (January 2018)
Reasons
Both “80% maximum power” and “80% maximum 30 minutes power” are technically correct methods. The most suitable method depends on the motor cooling technology (air cooled or water/oil cooled motors).
Sources (2)
“Both "80% maximum power" and "80% maximum 30 minutes power" are technically correct methods.”
“The most suitable method depends on the motor cooling technology (air cooled or water/oil cooled motors).”
UK raised a concern for air-cooled motors. For these motors, a 3 minute warm-up at 80 per cent maximum power can make declared net power figures much lower than the actual power. This is due to activation of thermal protection of the motor. In real world use, operation above 80 per cent maximum net power is only expected for a very short time. Most driving is expected to be in the 30 minutes power range.
Sources (3)
“UK raised a concern for air-cooled motors, where a 3 minute warm-up at 80 per cent maximum power can result in the declared net power figures being much lower than the actual power of the motor”
“due to activation of thermal protection of the motor”
“while in real world use, operating above 80 per cent maximum net power is only expected for a very short time, most driving is expected to be in the 30 minutes power range.”
For these reasons, the proposal is that manufacturers can make both choices (30 minutes power or maximum power), depending on their technology. This also aims to keep consistency with previous test results whenever possible.
Source
“Considering the arguments above, and also in order to maintain consistency with previous test results whenever possible, we propose that manufacturers can make both choices (30 minutes power or maximum power) depending on their technology.”
At some time in the evolution of the text, the parameter fm changed from a superscript to normal text. The formula then read “fa multiplied by fm” instead of “fa to the power of fm”. The proposal says that this is incorrect and should be corrected.
Sources (3)
“At some time in the evolution of the text, the parameter fm changed from being a superscript to being normal text”
“the formula changed from reading "fa to the power of fm" to reading "fa multiplied by fm").”
“This is incorrect and should be corrected.”
Document trail
- 2017-10ProposalECE/TRANS/WP.29/GRPE/2018/5Proposal by the expert from the International Organization of Motor Vehicle Manufacturers
- —Amended in sessionGRPE-76-23Proposal for amendments to ECE/TRANS/WP.29/GRPE/2018/5, submitted by the expert from UK and OICA
- —Working party adoptsECE/TRANS/WP.29/GRPE/76GRPE session report, para. 29 and Annex VII
- 2018-04Sent to WP.29ECE/TRANS/WP.29/2018/50Text that GRPE sent to WP.29 and AC.1
- 2018-06WP.29 adoptsECE/TRANS/WP.29/1139Adopted at the 175th session (session report, para. 118)
- 2018-12-29In forceC.N.621.2018.TREATIES-XI.B.16.85UN depositary notification
Q3Who is affected
Vehicle manufacturer
- For the three-minute bench run (5.3.1.3.), give a recommended speed within the speed range determined in paragraph 5.3.2.2.
- Make sure your diesel power correction factor αd at constant fuel rate follows the amended Annex 5 formula.
Component supplier
- No direct action for this role.
Technical service / Approval authority
- For the three-minute bench run (5.3.1.3.), make sure that the speed is within the speed range determined in paragraph 5.3.2.2.
- Make sure that the power test starts within a maximum of 1 minute after the three-minute bench run (5.3.1.3.).
- Make sure that the power correction factor (αd) for diesel engines follows the amended formula in Annex 5.
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ⓘ This report gives advice only. It is not legal or type-approval advice.