TECHNICAL. REPORT. Freinage des vkhicules routiers - Considkrations sur la dgfinition de la d&6/&a tion moyenne en rbgime

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1 TECHNICAL. REPORT IOITR First edition I 5 Dit docuent ag slechts op een stand-alone PC worden geinstalleerd. Gebruik op een netwerk is alleen. toestaan als een aanvullende licentieovereenkost voor netwerkgebruik et NEN is afgesloten. This docuent ay only be used on a stand-alone PC. Use in a network is only peritted when a suppleentary license agreeent for us in a network with NEN has been concluded. Braking of road vehicles - Considerations on the definition of ean fully developed deceleration Freinage des vkhicules routiers - Considkrations sur la dgfinition de la d&6/&a tion oyenne en rbgie Reference nuber IO/TR 13487: 1997(E) Dit docuent is een voorbeeld van NEN / This docuent is a preview by NEN

2 lo/tr 13487: 1997(E) Contents Page 1 Technical considerations Theoretical considerations Basic equations Deterination of the distance-related ean deceleration fro a(t) Evaluation procedures Evaluation Liits for the Deterination of the Mean Fully Developed Deceleration Evaluation liits in connection with the velocity signal Evaluation liits in connection with the deceleration signal (see figure 6) Evaluation liits in connection with the total braking tie Evaluation of liits by engineering judgeent Application Analytical functions...* Measureents * I All rights reserved. Unless otherwise specified, no part of this publication ay be reproduced or utilized in any for or by any eans, electronic or echanical, including photocopying and icrofil, without perission in writing fro the publisher. International Organization for tandardization Case postale 56 l CH-1211 Geneve 20 l witzerland Internet iso.ch x.400 c=ch; a=400net; p=iso; o=isocs; s=central Printed in witzerland ii Dit docuent is een voorbeeld van NEN / This docuent is a preview by NEN

3 0 I0 IO/TR 13487: 1997(E) Foreword I0 (the International Organization for tandardization) is a worldwide federation of national standards bodies (I0 eber bodies). The work of preparing International tandards is norally carried out through I0 technical coittees. Each eber body interested in a subject for which a technical coittee has been established has the right to represented on that coittee. International organizations, governental and non-governental, in liaison with IO, also take part in the work. I0 collaborates closely with the International Electrotechnical Coission (IEC) on all atters of electrotechnical standardization. The ain task of technical coittees is to prepare International tandards, but in exceptional circustances a technical coittee ay propose the publication of a Technical Report of one of the following types: - type 1, when the required support cannot be obtained for the publication of an International tandard, despite repeated efforts; - type 2, when the subject is still under technical developent or where for any other reason there is the future but not iediate possibility of an agreeent on an International tandard; - type 3, when a technical coittee has collected data of a different kind fro that which is norally published as an International tandard ( state of the art, for exaple). Technical Reports of types 1 and 2 are subject to review within three years of publication, to decide whether they can be transfored into International tandards. Technical Reports of type 3 do not necessarily have to be reviewed until the data they provide are considered to be no onger valid or useful. IO/TR 13487, which is a Technical Report of type 3, was prepared by Technical Coit Road vehicles, ubcoittee C 2, Brake sysfes and equipent. ee IOTTC 22,... III Dit docuent is een voorbeeld van NEN / This docuent is a preview by NEN

4 IO/TR 13487: 1997(E) 0 I0 Introduction ECE Regulation No. 13 Unifor Provisions Concerning the Approval of Vehicles of Categories M, N and 0 with Regard to Braking deterines the iniu legal braking perforance for new road vehicles at the tie of type-approval. This braking perforance is specified in ters of stopping distance and in ters of ean fully developed deceleration (fdd). The 08 series of aendents to ECE-R13 requires that both the above paraeters ust be fulfilled; furtherore, the 08 series of aendents prescribes the ethod of calculating the ean fully developed deceleration. The chosen ethod of calculating the fdd is based on the work done in lo/tc 22/C 2 Working Groups 6 and 10. For this reason, it is useful to suarize the background inforation on this subject in this I0 Technical Report, by describing the physical fundaentals and the connection between stopping distance and fdd; this will enable the persons responsible for deterining the braking perforance to analyse the results of testing, which are never exactly reproducible. Because the legislative text does not stipulate the easuring equipent nor specific easuring procedures, this Technical Report ay indicate alternative solutions to the Technical ervices and to the anufacturers of easuring equipent; it will also address prospective coputer-supported possibilities. In addition, the transition between different systes of units will be facilitated by this contribution. The prospective legislative text will concede alternative ethods of easuring the fdd; these are explicitly explained in this Technical Report. The report clearly indicates that in addition to the exact solutions for the fdd (see equations 16 and 29), certain approxiations (see equations 30, 31 and 33) are also perissible within the required accuracy, as docuented by theoretical considerations and corresponding practical easureents with a vehicle. For this reason, equation 31 was developed for coputer-aided and equation 33 for graphical evaluations. iv Dit docuent is een voorbeeld van NEN / This docuent is a preview by NEN

5 0 I0 IO/TR 13487: 1997(E) ybols vbol Unit Description a (9 a (9 a I a I ab9 ae af (t) ai, ai al U) aax as asly arns asn as29 as3 distance-dependent tie-dependent representative absolute value of 5 deceleration deceleration constant deceleration decelerations at the beginning and end of evaluation range on the linear approxiate solution for a (t) analytically given deceleration path with teporal drop individual deceleration values linear approxiate solution for a (t) axiu value in a tie-dependent deceleration path distance-related ean deceleration exaples of different distance-related approxiate value for the distance-related ean deceleration ean deceleration in accordance with Equation (33) nuerical approxiate value for the distance-related deceleration in accordance with Equation (31) ean at arnt ar (t) a1 () a2 (9 a3 (s) a1 (th a2 (t), a3 (t) d ds dt dv /s fdd B, E D F (t) i R tie-related ean deceleration approxiate value for the tie-related ean deceleration in accordance with Equation (34) analytically given deceleration path with teporal rise different distance-dependent deceleration paths different tie-dependent deceleration paths fdd according to ECE Regulation No. 13 distance differential tie differential speed differential ean fully developed deceleration distance distances at the start and end of evaluation range braking distance during the period of fdd distance path during the analytically given deceleration individual distance values af (t) braking distance during response tie and pressure build-up tie Dit docuent is een voorbeeld van NEN / This docuent is a preview by NEN

6 0 I0 R 0) ll s29 s3 l (t)9 s2 (th s3 (9 T t I t tb, te tr k t1 f2 i distance path during the analytically given deceleration ar (t) braking distances with different deceleration paths different distance paths total braking tie tie points in tie for the start and end of the evaluation range su of response tie and pressure build-up tie tie at the end of a stop point in tie at which the deceleration takes on the value aax at first tie point in tie at which the deceleration takes on the value aax at last tie V v (0 BY E F (t) Vi VR (0 VO Vl (09 v2 (th v3 (0 AasN, A as A ht, A asn k/h /s, k/h /s /s /s /s /s, k/h /s 0 / 0 test speed variable speed speeds at the start and end of evaluation range speed path during the analytically given deceleration af (t) individual speed values speed path during the analytically given deceleration ai3 (t) initial speed different speed paths related differences of ean decelerations (Tables 5 and 6) At 13 tie increent tie Dit docuent is een voorbeeld van NEN / This docuent is a preview by NEN

7 TECHNICAL I0 lo/tr 13487:1997(E) Braking of road vehicles - Considerations on the definition of ean fully developed deceleration 1 Technical considerations The ECE Regulation No. 13 Unifor Provisions Concerning the Approval of Vehicles with Regard to Braking deals in Annex 4 Braking Tests and Perforance of Braking ystes with the observance of certain stopping distances and certain ean fully developed decelerations under defined test conditions. The forulae applied for the judgeent of the stopping distance ordinarily have the structure I, +s,=f, xv+- V2 2xd, (1) where : s is the easured stopping distance, sr the distance correlated to the response and pressure buildup tie tr, sd the distance correlated to the ean fully developed deceleration phase, v the test speed and d the so-called ean fully developed deceleration. e.g. for passenger cars (vehicles of category Ml according to ECE-R13) the following values are valid: tr = 0,36 s, v = 22,22 /s and d = 5,8 If the stopping distance shall be easured in the diension and in addition the diension k/h shall be used for the speed, we get fro (1) in the case of Ml-vehicles the forula as it is known fro the Regulation No. 13: sio,lxv+- V2 150 (2) The proble is that there is until today no rule for deterining the ean fully developed deceleration (fdd) in such a way that it is coensurate to the existing legal requireents for stopping distances. A procedure which establishes fdd in such a way that it is in accordance with the stopping distance should additionally fulfil the following deands: - Mfdd shall not be design-restrictive concerning the easuring devices i.e. even pure deceleration easureents shall be evaluable. Dit docuent is een voorbeeld van NEN / This docuent is a preview by NEN

8 IO/TR 13487:1997(E) 0 I0 - The evaluation of the fdd shall allow the use of odern coputers as well as conventional ethods. - A representative part of the deceleration process ust be chosen for the evaluation. Until now, in national regulations in Europe, ean values have generally been based on tie. There is no indication on any of the analytical processes that ean value foration based on tie can lead to considerable errors, if the stopping distance or speed path is calculated with this tie-related ean value. Using various deceleration paths with the sae tie-related ean value, the following exaple shows that both the distance-related ean decelerations and the appertaining stopping distances assue different values. tarting fro the speed vo = 30 /s, in a tie interval of 0 to 6 s, the following deceleration paths are taken (Figure 1): a, (t)=d/s* a* (0 =-(8/s* -1/s3xt) a3 (0 =-(2/s* +l/s3 xt) (3) Tie Figure 1 - Different deceleration paths with the sae tie-related ean value Integration over tie gives the speeds (Figure 2): v,(t)=30/s-5/s*xt v2 (t)=30/s-(8/s*-0,5/s3xt)xt v, (t)=30/s-(2/s* +0,5/s3 xt)xt (4) 2 Dit docuent is een voorbeeld van NEN / This docuent is a preview by NEN

9 0 I0 lo/tr 13487: 1997(E) I 3 Tie Figure 2 - peed paths correlated to the decelerations in figure 1 Integration of the speeds over tie gives the distance paths (figure 3): s,(t)=30/sxt-2,5/s* Xt* s, (t)=30/sxt-@/s* -0,3/s3 xt)x- s, (t)=30/sxt-(2/s* +0,?/s3 xt)x- (5) 2 t 2 t I 0 i Tie Figure 3 - Distance paths correlated to the decelerations in Figure 1 In the case of different decelerations a (t) with the sae tie-related ean value, ajor deviations in the braking distance are apparent (Figure 3): s1 = 90 s2 = 72 sg=108 Dit docuent is een voorbeeld van NEN / This docuent is a preview by NEN 3

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