ISO/DIS 6627

Internal combustion engines -- Piston rings -- Expander/segment oil-control rings

Moteurs à combustion interne -- Segments de piston -- Segments racleurs régulateurs d'huile/Ressorts d'expansion

Standards Content (sample)

DRAFT INTERNATIONAL STANDARD
ISO/DIS 6627
ISO/TC 22/SC 34 Secretariat: ANSI
Voting begins on: Voting terminates on:
2021-04-05 2021-06-28
Internal combustion engines — Piston rings — Expander/
segment oil-control rings

Moteurs à combustion interne — Segments de piston — Segments racleurs régulateurs d'huile/Ressorts

d'expansion
ICS: 43.060.10
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
This document is circulated as received from the committee secretariat.
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ISO/DIS 6627:2021(E)
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NOTIFICATION OF ANY RELEVANT PATENT
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PROVIDE SUPPORTING DOCUMENTATION. ISO 2021
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ISO/DIS 6627:2021(E)
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ii © ISO 2021 – All rights reserved
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ISO/DIS 6627:2021(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Symbols and abbreviated terms ........................................................................................................................................................... 1

5 Ring types and designations..................................................................................................................................................................... 3

5.1 Types of expander/rail oil-control rings .......................................................................................................................... 3

5.2 General features ..................................................................................................................................................................................... 3

5.3 Designation examples ....................................................................................................................................................................... 5

6 Common features ................................................................................................................................................................................................. 5

6.1 Expander ...................................................................................................................................................................................................... 5

6.1.1 Design considerations ................................................................................................................................................. 5

6.1.2 Without surface treatment ...................................................................................................................................... 6

6.1.3 Nitrided surface (NX) ................................................................................................................................................... 6

6.1.4 Tab angle ................................................................................................................................................................................. 6

6.1.5 Expander dimensions .................................................................................................................................................. 7

6.2 Rail features ............................................................................................................................................................................................... 7

6.2.1 Chromium-plated peripheral surface ............................................................................................................ 7

6.2.2 Nitrided surface codes NS010 to NS050 ..................................................................................................... 7

6.2.3 PVD coated peripheral surface ............................................................................................................................ 8

6.2.4 Rail dimensions ................................................................................................................................................................. 8

6.3 Expander/rail assembly ...............................................................................................................................................................10

7 Dimensions ..............................................................................................................................................................................................................11

8 Materials ....................................................................................................................................................................................................................11

9 Tangential force and nominal unit pressure ........................................................................................................................11

9.1 Tangential force, F ..........................................................................................................................................................................11

9.2 Nominal Unit Pressure ..................................................................................................................................................................11

9.3 Classes of nominal unit pressure .........................................................................................................................................12

Bibliography .............................................................................................................................................................................................................................13

© ISO 2021 – All rights reserved iii
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ISO/DIS 6627:2021(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 normally 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 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 different 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 document 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/ patents).

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 voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following

URL: www .iso .org/ iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 34,

Propulsion, powertrain and powertrain fluids.

This third edition cancels and replaces the second edition (ISO 6627:2011), which has been technically

revised.
The main changes compared to the previous edition are as follows:
— Previous nomenclature referred to the rails as segments.
— Barrel faced rail was added.
— PVD specification for rails was added.
— Figures and tables were revised.
— New dimension introduced for expander.
— Applicable bore diameter range increased to 135mm.
A list of all parts in the ISO 6627 series can be found on the ISO website.
iv © ISO 2021 – All rights reserved
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ISO/DIS 6627:2021(E)
Introduction

ISO 6627 is one of a series of International Standards dealing with piston rings for reciprocating internal

combustion engines. Others are ISO 6621, ISO 6622, ISO 6623; ISO 6624, ISO 6625 and ISO 6626 (see

Clause 2 and the Bibliography).

The common features and dimensional tables included in ISO 6627 represent a broad range of variables.

In selecting a ring type, the designer will above all need to consider the particular operating conditions.

Moreover, it is essential that the designer refer to the specifications and requirements of ISO 6621-3

and ISO 6621-4 before completing the selection.
© ISO 2021 – All rights reserved v
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DRAFT INTERNATIONAL STANDARD ISO/DIS 6627:2021(E)
Internal combustion engines — Piston rings — Expander/
segment oil-control rings
1 Scope

This International Standard specifies the essential dimensional features of expander/rail oil-control

rings, without providing a complete product description (because expander-rail designs vary from

piston-ring manufacturer to piston-ring manufacturer, the interaction between the manufacturer and

the client will determine specific design details).

This International Standard applies to expander/rail oil-control rings of nominal diameters ranging

from 40 mm to 135 mm for reciprocating internal combustion engines for road vehicles and other

applications. It also applies to piston rings for compressors working under analogous conditions.

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 6621-2, Internal combustion engines — Piston rings — Part 2: Inspection measuring principles

ISO 6621-3, Internal combustion engines — Piston rings — Part 3: Material specifications

ISO 6621-4, Internal combustion engines — Piston rings — Part 4: General specifications

ISO 6626, Internal combustion engines — Piston rings — Coil-spring-loaded oil control rings

3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO6621-1 apply.

4 Symbols and abbreviated terms

For the purposes of this International Standard, the symbols and abbreviated terms in Table 1 apply.

© ISO 2021 – All rights reserved 1
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ISO/DIS 6627:2021(E)
Table 1 — Symbols and abbreviated terms
Symbol
abbreviated Description
terms
a Rail radial wall thickness
a Expander radial thickness excluding tab
a Expander radial thickness
a Assembly radial thickness
a Tab radial thickness
a Pad radial thickness
d Nominal ring assembly diameter (nominal bore diameter)
h Nominal assembly axial width
h Rail face contact width
h Barrel gauge width
h Expander axial width
h Rail axial width near inside diameter (ID), after coiling

h Rail axial width near outside diameter (OD), after coiling and surface treatment or plating

h Nominal rail axial width
h Expander axial width over pads
h Pad height
h Axial distance between height of expander tab and height of ex
...