ISO 12251:2011
(Main)Diesel engines — Clamp mounted CR fuel injectors — Mounting dimensions
Diesel engines — Clamp mounted CR fuel injectors — Mounting dimensions
ISO 12251:2011 specifies dimensional requirements for clamp mounted CR fuel injectors and their corresponding cylinder head features in diesel engines.
Moteurs diesels — Injecteurs de combustible pour rampe commune fixés par patte — Dimensions de montage
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 12251
First edition
2011-02-01
Diesel engines — Clamp mounted CR fuel
injectors — Mounting dimensions
Moteurs diesels — Injecteurs de combustible pour rampe commune
fixés par patte — Dimensions de montage
Reference number
ISO 12251:2011(E)
©
ISO 2010
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ISO 12251:2011(E)
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ii © ISO 2011 – All rights reserved
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ISO 12251:2011(E)
Contents Page
Foreword .iv
1 Scope.1
2 Symbols.1
3 General requirements .2
3.1 Clamp mounting arrangement .2
3.2 Injector guiding dimensions .3
3.3 Concentricity of the nozzle shaft .3
4 Dimensions and tolerances.5
4.1 Type A, clamp mounted CR fuel injectors with straight capnut.5
4.2 Type B, clamp mounted CR fuel injectors with stepped capnut .7
5 Other specifications.9
6 Designation .9
© ISO 2011 – All rights reserved iii
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ISO 12251:2011(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 12251 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 7, Injection
equipment and filters for use on road vehicles.
iv © ISO 2011 – All rights reserved
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INTERNATIONAL STANDARD ISO 12251:2011(E)
Diesel engines — Clamp mounted CR fuel injectors — Mounting
dimensions
1 Scope
This International Standard specifies dimensional requirements for clamp mounted CR fuel injectors and their
corresponding cylinder head features in diesel engines.
According to the injector nozzle capnut, the clamp mounted CR fuel injectors can be divided into two types:
a) Type A, where the nozzle capnut is straight (see Figure 4).
b) Type B, where the nozzle capnut is stepped (see Figure 5).
Each clamp mounted CR fuel injector type is subdivided by a series of different sizes.
NOTE This differentiation corresponds to the relationship between the two guide diameters of the clamp mounted CR
fuel injectors.
2 Symbols
For the purposes of this document, the following symbols apply:
D = injector shaft diameter
1
D = injector upper guide diameter
2
D = capnut diameter
3
D = injector lower guide diameter
4
D = injector nozzle shaft diameter
5
d = bore for upper guide diameter
6
d = bore for lower guide diameter
7
d = bore for nozzle shaft
8
l = overall injector length
1
l = distance between sealing face and upper guide diameter of injector
2
l = overlapping (upper guide diameter/cylinder head)
3
l = injector clamping width
4
l = clamp width
5
l = injector clamping height
6
l = distance between sealing face and datum B on injector
7
l = distance between sealing face and datum C on injector
8
NOTE l and l are dependent on the cylinder head design as agreed between injector manufacturer and customer.
7 8
© ISO 2011 – All rights reserved 1
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ISO 12251:2011(E)
3 General requirements
3.1 Clamp mounting arrangement
A typical clamp mounting arrangement is shown in Figure 1 (schematically).
Key
l overall injector length
1
l injector clamping height
6
1 top of injector (e.g. hydraulic connection)
2 injector sealing face
NOTE The injector clamping height varies depending on engine application and is agreed between manufacturer and
customer.
Figure 1 — Typical injector clamp mounting arrangement
2 © ISO 2011 – All rights reserved
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ISO 12251:2011(E)
3.2 Injector guiding dimensions
The important injector guiding dimensions are shown in Figure 2 (schematically).
Key
l o
...
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