1、BSI Standards Publication BS ISO 28741:2013 Road vehicles Spark- plugs and their cylinder head housings Basic characteristics and dimensionsBS ISO 28741:2013 BRITISH STANDARD National foreword This British Standard is the UK implementation of ISO 28741:2013. It supersedes BS ISO 28741:2009 which is
2、withdrawn. The UK participation in its preparation was entrusted to Technical Committee MCE/22, Engines for road vehicles. A list of organizations represented on this committee can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a
3、 contract. Users are responsible for its correct application. The British Standards Institution 2013. Published by BSI Standards Limited 2013 ISBN 978 0 580 73389 5 ICS 43.060.50 Compliance with a British Standard cannot confer immunity from legal obligations. This British Standard was published und
4、er the authority of the Standards Policy and Strategy Committee on 30 November 2013. Amendments issued since publication Date Text affectedBS ISO 28741:2013 ISO 2013 Road vehicles Spark-plugs and their cylinder head housings Basic characteristics and dimensions Vhicules routiers Bougies dallumage et
5、 leur logement dans la culasse Caractristiques lmentaires et dimensions INTERNATIONAL STANDARD ISO 28741 Second edition 2013-11-15 Reference number ISO 28741:2013(E)BS ISO 28741:2013ISO 28741:2013(E)ii ISO 2013 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO 2013 All rights reserved. Unless oth
6、erwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
7、 below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in SwitzerlandBS ISO 28741:2013ISO 28741:2013(E) ISO 2013 All rights reserved iii Contents
8、 Page Foreword iv Introduction v 1 Scope . 1 2 Normative references 1 3 T erms and definitions . 1 4 Terminals . 3 4.1 Solid post terminal dimensions 3 4.2 Threaded terminal dimensions 4 5 Dimensions, threads, and related items 4 5.1 Spark-plug reach 4 5.2 Gasket 5 5.3 Threads, limiting dimensions,
9、and tolerances . 5 6 Other dimensions of spark-plugs and their cylinder head housings .6 7 Installation tightening torque 6 8 Spark-plug dimensions 7 8.1 Spark-plugs with flat seating 7 8.2 Spark-plugs with conical seating 14 9 Cylinder head housings 19 9.1 Cylinder head housing for spark-plugs with
10、 flat seating .19 9.2 Cylinder head housing for spark-plugs with conical seating .21 Annex A (normative) Spark-plugs with half thread and their cylinder head housings 22 Annex B (informative) Optional terminals for compact spark-plugs 24 Annex C (informative) Optional combination cylinder head housi
11、ng for spark-plugs with conical or flat seating 26 Bibliography .27BS ISO 28741:2013ISO 28741:2013(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normall
12、y carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the
13、work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the d
14、ifferent approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives). Attention is drawn to the possibility that some of the elements of this documen
15、t may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/p
16、atents). Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement. For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO pri
17、nciples in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information The committee responsible for this document is ISO/TC 22, Road vehicles, Subcommittee SC 1, Ignition equipment. This second edition cancels and replaces the first edition (ISO 28741:2009), wh
18、ich has been technically revised. It also incorporates the Technical Corrigendum ISO 28741:2009/Cor1:2009.iv ISO 2013 All rights reservedBS ISO 28741:2013ISO 28741:2013(E) Introduction The purpose of this International Standard is to provide a compact and concise specification on spark-plugs and the
19、ir cylinder head housings, which replaces the large number of existing individual International Standards on each type of spark-plug. It is intended to specify the main properties, the design requirements, and the dimensions of most of the existing types of spark-plugs and their cylinder head housin
20、gs. In this way, the user can work with one comprehensive International Standard valid for most types of spark-plugs, instead of a number of International Standards, each of which is specified for one type only. The testing of spark-plugs is covered in ISO 11565. ISO 2013 All rights reserved vBS ISO
21、 28741:2013BS ISO 28741:2013Road vehicles Spark-plugs and their cylinder head housings Basic characteristics and dimensions 1 Scope This International Standard specifies the main properties and dimensions of spark-plugs, including the terminals and the dimensions of their cylinder head housings, for
22、 use with spark-ignition engines. This International Standard does not cover screened and waterproof spark-plugs (see ISO 3412, ISO 3895, and ISO 3896). 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its appl
23、ication. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 68-1, ISO general purpose screw threads Basic profile Part 1: Metric screw threads ISO 261, ISO general purpose metric screw th
24、reads General plan ISO 965-1, ISO general-purpose metric screw threads Tolerances Part 1: Principles and basic data ISO 965-3, ISO general purpose metric screw threads Tolerances Part 3: Deviations for constructional screw threads ISO 4095, Aerospace Bihexagonal drives Wrenching configuration Metric
25、 series ISO 6518-1, Road vehicles Ignition systems Part 1: Vocabulary 3 T erms a nd definiti ons For the purposes of this document, the terms and definitions given in ISO 6518-1 and the following apply. 3.1 installed height l distance from the contact point of the cylinder head to the top of the spa
26、rk-plug terminal, including the compressed gasket thickness with the spark-plug installed at the specified installation torque Note 1 to entry: For conical seating, the contact point is defined from the gauge point of the seat. 3.2 spark-plug thread size nominal size of the spark-plug thread used to
27、 interface between the spark-plug and the cylinder head thread Note 1 to entry: These are standard metric threads, with the exception of the M14 1,25 thread. 3.3 hexagon/bi-hexagon feature of the spark-plug shell that is used to install the spark-plug into the cylinder head, interfacing with the ins
28、tallation socket while the spark-plug is installed into the cylinder head Note 1 to entry: A bi-hexagon is a 12-point installation feature, which requires that a 12-point socket wrench be used to install the spark-plug. INTERNATIONAL ST ANDARD ISO 28741:2013(E) ISO 2013 All rights reserved 1BS ISO 2
29、8741:2013ISO 28741:2013(E) 3.4 conical seating conical section of the spark-plug shell on some spark-plug types, which is used for the seal interface between the spark-plug and the cylinder head Note 1 to entry: There is typically no gasket used between the conical mating surfaces. 3.5 f la t s ea t
30、 ing flat surface of some spark-plug types which is perpendicular to the spark-plug axis and is used for the seal interface between the spark-plug and the cylinder head Note 1 to entry: This seal typically uses a gasket between the flat seat of the spark-plug and the mating flat surface of the cylin
31、der head. 3.6 insulator diameter e nominal diameter of the insulator in a defined region of the insulator between the top of the shell and the terminal of the spark-plug, which interfaces with a corresponding region of the high-voltage boot of the ignition lead or ignition coil Note 1 to entry: The
32、fit is the key to suppression of high-voltage leakage around the spark-plug insulator (flashover). 3.7 high-voltage terminal part of the spark-plug that is used as the contact point between the high-voltage ignition source and the spark-plug Note 1 to entry: The connection between the high-voltage i
33、gnition source and the spark-plug terminal can be made with a threaded fastener, with a snap clip that interfaces with the solid terminal or by spring-loaded mechanical contact. 3.8 installation tightening torque rotational force applied to the spark-plug hexagon to ensure proper seating and sealing
34、 of the spark-plug to the cylinder head Note 1 to entry: The value of the correct installation tightening torque can vary from conditions that affect the friction between the spark-plug threads and the cylinder head threads. These include cylinder head material, spark-plug shell plating, thread lubr
35、ication, and contamination from combustion deposits. It is advisable to ensure that spark-plugs are not over-torqued during installation, as this can damage spark-plug integrity and can result in engine damage. Spark-plugs with smaller thread sizes require a lower installation tightening torque. 3.9
36、 spark-plug reach a distance from the spark-plug seating surface (flat seat) or from the gauge diameter (conical seat) to the point on the shell designed to be aligned with the combustion chamber surface on the cylinder head with the spark-plug properly installed Note 1 to entry: It is advisable to
37、design the spark-plug reach and the cylinder head housing in such a way that they match, so as to ensure correct fit of the spark-plug into the combustion chamber. 3.10 spark-plug projection b-a distance that any part of the spark-plug projects past the spark-plug reach into the combustion chamber N
38、ote 1 to entry: It is important to consider this dimension for possible interference with the engine piston at top dead centre.2 ISO 2013 All rights reservedBS ISO 28741:2013ISO 28741:2013(E) 4 Terminals 4.1 Solid post terminal dimensions The dimensions of solid post terminals shall be in accordance
39、 with Figures 1 and 2. Nuts for use with threaded terminals shall have the same external dimensions as those of the solid post terminal, and shall have internal threads to 6H tolerance prior to assembly on the threaded terminals. Dimensions in millimetres Key 1 reference plane a For existing product
40、s, values between 7 and 30 are allowed. Figure 1 Solid post terminal The measurement of the minimum diameter of 6,3 mm shall be taken at any or all points around the post circumference. A ring gauge shall be used for measuring the maximum diameter of 6,4 mm. ISO 2013 All rights reserved 3BS ISO 2874
41、1:2013ISO 28741:2013(E) Dimensions in millimetres Key 1 reference plane Figure 2 Solid post terminal for M10 1 bi-hex 12 mm spark-plugs The measurement of the minimum diameter of 5,3 mm shall be taken at any or all points around the post circumference. A ring gauge shall be used for measuring the ma
42、ximum diameter of 5,4 mm. 4.2 Threaded terminal dimensions The dimensions of threaded terminals shall be in accordance with Figure 3. Dimensions in millimetres Key a Length of usable thread. b Cylindrical part. c Depending on manufacturing process, tolerance class 7e is acceptable on finished produc
43、t. Figure 3 Threaded terminal 5 Dimensions, threads, and related items 5.1 Spark-plug reach The spark-plug reach shall be in accordance with Table 5 or 7 (see also Figures 4 to 15).4 ISO 2013 All rights reservedBS ISO 28741:2013ISO 28741:2013(E) The following basic types of spark-plug reach are defi
44、ned: Short: S Medium: M Long: L Extended long: EL Extra long: XL Extended extra long: EXL 5.2 Gasket When unused spark-plugs with flat seating have been tightened once with a torque, as specified in Clause 7 and Table 3, on threads that are clean, smooth, and dry, the gasket thickness shall be as sp
45、ecified in Table 3. Non-captive gaskets may be used in special cases. 5.3 Threads, limiting dimensions, and tolerances The threads of spark-plugs and the corresponding tapped holes in the cylinder heads shall conform to ISO 68-1, ISO 261, ISO 965-1, and ISO 965-3. Their limiting dimensions, minor di
46、ameters, basic profiles, and initial clearances are specified in Tables 1 and 2, respectively. Table 1 Limiting dimensions Dimensions in millimetres Thread size Toler- ance class Dimension Major diameter Pitch diameter Minor diameter max. min. max. min. max. min. M18 1,5 6e Plug thread (on finished
47、plug) 17,933 17,697 16,959 16,819 16,092 15,845 a 6H Tapped hole in the cylinder head not specified 18,000 17, 216 17,026 16,676 16,376 M14 1,25 6e Plug thread (on finished plug) 13,937 13,725 13,125 12,993 12,404 12,181 b 6H Tapped hole in the cylinder head not specified 14,000 13,368 13,188 12,912
48、 12,647 M12 1,25 6e Plug thread (on finished plug) 11,937 11,725 11,125 10,993 10,404 10,181 b 6H Tapped hole in the cylinder head not specified 12,000 11,368 11,188 10,912 10,647 M10 1 6g Plug thread (on finished plug) 9,974 9,794 9,324 9,212 8,747 8,563 c 6H Tapped hole in the cylinder head not sp
49、ecified 10,000 9,500 9,350 9,153 8,917 aWith a root radius 0,150 mm (0,1 P). bWith a root radius 0,125 mm (0,1 P). cWith a root radius 0,1 mm (0,1 P). ISO 2013 All rights reserved 5BS ISO 28741:2013ISO 28741:2013(E) T a b l e 2 M i n o r d i a m e t e r s , b a s i c p r o f i l e s , a n d i n i t i a l c l e a r a n c e s f o r t h r e a d s u s e d Dimensions in millimetres Thread size Minor diameter ad 3max Fundamental deviation bes M18 1,5 6e d 3max= (16,37
