WO2017067855A1

WO2017067855A1 - Fuel injector nozzle shield

Info

Publication number: WO2017067855A1
Application number: PCT/EP2016/074738
Authority: WO
Inventors: Nathan Peter KEELER; Simon Phillips
Original assignee: Delphi International Operations Luxembourg S.À R.L.
Priority date: 2015-10-20
Filing date: 2016-10-14
Publication date: 2017-04-27
Also published as: EP3365549B1; GB201518531D0; EP3365549A1

Abstract

A shield (36) is adapted to be arranged between the nozzle (30) of a fuel injector (26) and an engine block (10), the shield (36) having a metallic body comprising a tubular portion (38) inside of which the cylindrical nozzle of the fuel injector can be press-fitted with interference and, that is able to be inserted with clearance (C) in a cylindrical hole of the engine block. The shield (36) further comprises a thermal protecting member (56) arranged over the external face (54) of the tubular portion.

Description

Fuel injector nozzle shield TECHNICAL FIELD

The present invention relates generally to a fuel injector and more particularly to shield to inserted between the nozzle of the injector and an engine block. BACKGROUND OF THE INVENTION

Fuel injectors are typically inserted in deep well provided in engine block. More precisely, in each well is press-fitted an injector pocket member having a large section portion outwardly opening on the top face of the engine block and, a small section portion extending from the large portion and ultimately opening in a combustion chamber of the engine. In the injector pocket member is placed a fuel injector having a main large section body, that is arranged in the large section portion of the injector pocket and, a narrow section nozzle arranged in the small section portion of the injector pocket.

More precisely, around the nozzle is press-fitted a tubular shield typically machined from copper alloy that has excellent thermal conductivity properties. The press-fit intimately links the shield to the nozzle and, around the shield is reserved an annular air gap of few tenths of millimeters between outer face of the shield and the inner face of the small section portion of the injector pocket member.

Furthermore, at an extremity of the shield is provided a collar forming a disc outwardly extending from the tubular shield toward a peripheral circular edge. In use, the collar is compressed between a shoulder face of the injector pocket, which is between the large and the small portions, and a shoulder face of the injector nut of the fuel injector. Ultimately, the injector is maintained in place by a bracket member arranged over its top and that is screwed in the engine block downwardly biasing the injector and compressing the collar.

In use, the shield enables in use to evacuate the heat generated in a combustion chamber and transferred to the nozzle, from said nozzle toward the engine block and, the collar seals the large section portion, in which is fuel at low pressure, from the small section portion. Constant enhancement of performances requires improvement of the thermal protection of the nozzle.

SUMMARY OF THE INVENTION

It is an object of the invention to resolve or at least mitigate the above mentioned problem by providing shield adapted to be arranged between the nozzle of a fuel injector and an engine block. The shield has a metallic body comprising a tubular portion inside of which the cylindrical nozzle of the fuel injector can be press-fitted with interference and, that is able to be inserted with clearance in a cylindrical hole of the engine block.

The shield further comprises a thermal protecting member arranged over the external face of the tubular portion.

The thermal protecting member has a lower thermal conductivity than the metallic body.

In an embodiment, the thermal protecting member is integral to the tubular portion, for instance, the thermal protecting member can be a coating of the external cylindrical face of the tubular member.

In said embodiment, the coating can comprise tin.

Also, the metallic body of the shield is made of copper alloy.

The shield further comprises a collar forming a thick disc radially outwardly extending from an extremity of the tubular portion. The collar has a first face, or upper face, an opposed second face, or under face, and, a peripheral face joining the first face to the second face. In use, the collar is compressed between a shoulder face of the fuel injector abutting against the first face and, a shoulder face provided in the engine block abutting against the second face of the collar.

Particularly, the shield further comprises a fuel protecting member arranged over the peripheral face of the collar.

The fuel protecting member further extends over the first face of the collar.

In an embodiment, the fuel protecting member is integral to the collar, for instance, the fuel protecting member can be a coating the collar. Said coating comprises tin. In an embodiment, the heat protecting coating and the fuel protecting coating are made of the same material.

In another embodiment, the heat protecting member and the fuel protecting member are made of different materials.

the invention further extends to a fuel injector having a cylindrical nozzle for delivering fuel in a combustion chamber of an internal combustion engine and, a shield press-fitted over said cylindrical nozzle, the shield being as described above. BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is now described by way of example with reference to the accompanying figure that is an axial section of the arrangement of the fuel injector in an engine block. DESCRIPTION OF THE PREFERRED EMBODIMENTS

The arrangement of a fuel injector in an engine block is now described in reference to the figure. The description uses for simplification and clarity purposes the top-down arbitrary orientation of the figure without any intent to limit the scope of protection defined by the claims.

An engine block 10 is provided with a coolant gallery 12, represented horizontal and, with a vertical opening 14 extending along a main axis Z and, in which is inserted with press-fit an injector pocket 16. The injector pocket 16 has a tubular body having a peripheral wall defining an internal volume V comprising a large section portion 18 upwardly opening in a top face of the engine block 10 and, a small section portion 20 downwardly opening in a combustion chamber 22 of the engine, said large and small section being joined via a transverse shoulder face 24.

Inside said internal volume V is arranged a fuel injector 26 having a large section actuator member 28 from the bottom of which axially Z extends a narrow cylindrical nozzle assembly 30, said actuator member and nozzle fixed to each other by a cap nut 32 defining another transverse shoulder face 34.

Press fitted onto the cylindrical nozzle 30 is a tubular shield 36, having a tubular portion 38 at an extremity of perpendicularly extends a collar 40. The tubular portion 38 is press fitted on the cylindrical nozzle 30 and it extends from an open lower extremity 42 up to an opposite open upper extremity 44 where outwardly perpendicularly the collar 40 is. As visible on the figure, the collar 40 has an upper face 46 radially extending from an internal circular edge that is common with the internal face 48 of the tubular portion to, an external circular edge that is common with a peripheral cylindrical face 50 of the collar. Similarly, parallel to the upper face 46, the collar 40 has an under face 52 radially extending toward an external circular edge that is common with the peripheral cylindrical face 50 of the collar. On the illustration the under face 52 merges with the cylindrical external face 54 of the tubular portion via a fillet, although this could be another shape such as a chamfer or a straight edge.

Although several materials may be utilized for manufacturing the shield 36, it is known to use a copper alloy, such as Tellurium Copper (CuTeP), which has excellent thermal conductivity.

The external face 54 of the tubular portion is covered by a thermal protecting coating 56 having a thermal conductivity inferior to the conductivity mentioned above for the core of the shield, one of the preferred materials for said thermal coating being a tin alloy.

Also, the upper face 46 of the collar is covered by a fuel protecting coating 58 preventing direct fuel contacts between the copper alloy shied and fuel that may be present in the injector pocket 16. Although the materials of the thermal coating 56 and of the fuel protecting coating 58 may be chosen different from each other, having the same tin alloy for both coatings is preferred.

Alternatively, the surface coatings that are integral to the shield, one may prefer to arrange independent metallic sleeves fixed over the tubular portion and over the upper and peripheral faces of the shield 36.

Arranged for use as presented on the figure, the large actuator portion 28 occupies the large section of the injector pocket 16 and, the narrow nozzle 30 around which is press fitted the shield 36, is engaged with a clearance C of few tenths of millimeters in the small section portion 20 of the injector pocket. The collar 40 is axially Z compressed between the shoulder face 34 of the fuel injector and the shoulder face 24 of the injector pocket, the compression force being generated by a clamp, not shown, screwed on the top face of the engine block downwardly compressing the fuel injector inside the injector pocket. The thermal coating 56 limits the heat transfer from the vicinity of the combustion chamber 22 toward the nozzle 30 while the heat of the nozzle may be channeled by the tubular portion of the shield toward the collar then, through the contact between the under face of the collar to the injector pocket.

LIST OF REFERENCES

Z main axis

V internal volume of the injector pocket

C clearance

10 engine block

12 coolant gallery

14 opening

16 inj ector pocket

18 large section portion of the injector pocket

20 small section portion of the injector pocket

22 combustion chamber

24 shoulder face of the injector pocket

26 fuel injector

28 actuator member

30 nozzle

32 capnut

34 shoulder face of the fuel injector

36 shield

38 tubular portion of the shield

40 collar

42 open lower extremity of the shield

44 open upper extremity of the shield

46 upper face of the collar - first face

48 internal face of the tubular wall

50 peripheral face of the collar

52 under face of the collar - second face

54 external face of the tubular portion

56 thermal protecting coating

58 fuel protecting coating

Claims

1. Shield (36) adapted to be arranged between the nozzle (30) of a fuel injector (26) and an engine block (10), the shield (36) having a metallic body comprising a tubular portion (38) inside of which the cylindrical nozzle of the fuel injector can be press-fitted with interference and, that is able to be inserted with clearance (C) in a cylindrical hole of the engine block and,

the shield (56) further comprising a collar (40) forming a thick disc radially outwardly extending from an extremity of the tubular portion (38); the collar (40) having a first face (46), or upper face, an opposed second face (52), or under face, and, a peripheral face (50) joining the first face (46) to the second face (52);

the collar (40) being, in use, compressed between a shoulder face (34) of the fuel injector abutting against the first face (46) and, a shoulder face (24) provided in the engine block abutting against the second face (52) of the collar, characterized in that

the metallic body of the shield is made of copper alloy, the shield (36) further comprising a thermal protecting member (56) arranged over the external face (54) of the tubular portion and also a fuel protecting member (58) arranged over the peripheral face (50) of the collar.

2. Shield (36) as claimed in the preceding claim wherein the thermal protecting member (56) has a lower thermal conductivity than the metallic body.

3. Shield (36) as claimed in any one of the preceding claims wherein the thermal protecting member (56) is integral to the tubular portion.

4. Shield (36) as claimed in any one of the preceding claims wherein the thermal protecting member (56) is a coating of the external cylindrical face (54) of the tubular member.

5. Shield (36) as claimed in claim 4 wherein said coating (56) comprises tin.

6. Shield (36) as claimed in any one of the preceding claims wherein the fuel protecting member (58) further extends over the first face (46) of the collar.

7. Shield (36) as claimed in any one of the preceding claims wherein the fuel protecting member (58) is integral to the collar.

8. Shield (36) as claimed in claim 7 wherein the fuel protecting member (58) is a coating the collar.

9. Shield (36) as claimed in claim 8 wherein said coating comprises tin.

10. Shield (36) as claimed in the combination of claims 5 and 11 wherein the heat protecting coating (56) and the fuel protecting coating (58) are made of the same material.

11. Shield (36) as claimed in the combination of claims 5 and 9 wherein the heat protecting member (56) and the fuel protecting member (58) are made of different materials.

12. Fuel injector (26) having a cylindrical nozzle (30) for delivering fuel in a combustion chamber (22) of an internal combustion engine and, a shield (36) press-fitted over said cylindrical nozzle, the shield (36) being as claimed in any one of the preceding claims.