GB2304815A

GB2304815A - Pressurising apparatus for fuel injection line

Info

Publication number: GB2304815A
Application number: GB9616818A
Authority: GB
Inventors: Norbert Dipl Ing Binzer
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-08-29
Filing date: 1996-08-09
Publication date: 1997-03-26
Anticipated expiration: 2016-08-09
Also published as: SE508719C2; GB2304815B; GB9616818D0; SE9603116D0; NL1003861C2; DE19531743C1; IT1286695B1; SE9603116L; ITFI960194A1; FR2738297B1; FR2738297A1; NL1003861A1

Description

1 2304815 Pressurising apparatus The invention concerns a pressurising

apparatus and a fuel injection line for use with such an apparatus.

In an internal combustion engine fuel injection lines serve to feed the fuel which is supplied by an injection pump to a respective injection nozzle from which it then passes into the combustion chanber. For that purpose such a fuel injection line generally has at each of its two ends a respective sealing nipple which is formed by upsetting thereon and which, at its side remote from the fuel injection line, has a main sealing surface with which, in normal operation, at one end it is pressed against a co-operating sealing surface of a counterpart portion of the injection pump or, at the other end of the fuel injection line, against a co-operating sealing surface of a counterpart portion of the injection nozzle. The fuel injection line is fixed in position for example by means of respective union nuts.

The main sealing surface of the sealing nipple may be in the form of a truncated cone -or a portion of a sphere. No=nally it has a front sealing edge with which it blends into an end face of the sealing nipple, which extends transversely to the longitudinal direction of the fuel injection line.

The co-operating surfaces of the counterpart portions of the injection pump and the injection nozzle respectively are generally of a hollow conical configuration, the opening angle of the hollow conical configuration being somewhat larger than that of the frustoconical main sealing surface or the conical configuration which in the region of the sealing edge can applied tangentially against a spherical main sealing surface.

By virtue of that arrangement, when the injection line is fitted, contact occurs between the main sealing surface of the respective sealing nipple and the co-operating sealing surface of the respective counterpart portion, at the small diameter of the sealing surface. When the union nut is tightened, the sealing edge of the relatively soft sealing nipple adapts to the co-operating sealing surface by experiencing plastic deformation.

Whenever the injection line is re-fitted, for example after v 1 2 maintenance operations on the injection nozzle or the injection pump, the union nut has to be tightened with a higher degree of torque as ever increasing deforTnation of the sealing edge has to be produced on each such occasion.

Now, it is sometimes necessary for injection lines of that kind, before they are first fitted to an internal combustion engine, to be subjected to an increased internal pressure for example for test purposes, in other wards, a pressure which may be two to three times the normal operating pressure. For that purpose, such an injection line is pressure-tightly connected at its ends to counterpart portions of a pressurising apparatus, in a similar fashion to the way it is fitted to an internal combustion engine. In that case once again each of the sealing nipples is pressed against a co-operating sealing surface of a counterpart portion of the pressurising apparatus, under such a high force as to produce a connection affording sealing integrity, which can withstand the pressures which are generated in such a pressurising apparatus and which, particularly in the case of fuel injection lines for Diesel engines, can assume very high values.

If now the main 'sealing surface which is employed in normal operation is also used with its sealing edge for producing the sealed connection to the counterpart portions of the pressu:iising apparatus, very severe plastic deformation already occurs here, and that plastic deformation can severely impair or even render impossible normal operation upon subsequent use on an internal combustion engine.

According to the present invention there is provided a pressurising apparatus for subjecting a fuel injection line having a sealing nipple at least at its one end for an internal combustion engine to an increased internal pressure outside normal operation, which sealing nipple includes a main sealing surface which in normal operation can be pressed against a co-operating sealing surface of a counterpart portion of the engine or the fuel pump respectively, the pressurising apparatus comprising a counterpart portion which includes a co-operating sealing surface of such a configuration and arrangement that it comes into pressure-tight pressing engagement with an auxiliary sealing surface of the sealing nipple so that when the sealing nipple is clamped into the pressurising apparatus the main sealing surface of the sealing nipple is not exposed to a deforming 3 loading.

The invention also provides a fuel injection line for use with a pressurising apparatus according to the immediately preceding paragraph, ccmprising at least one sealing nipple including a main sealing surface with which it is capable of being pressed sealingly during normal operation against a co-operating sealing surface of a counterpart portion of an internal combustion engine or a fuel pump, and an auxiliary sealing surface with which it is capable of being pressure-tightly pressed against a co-operating sealing surface of a counterpart portion of the pressurising apparatus so that the main sealing surface is not subjected to a deforming loading.

By virtue of the arrangement according to the invention a sealing connection between the respective counterpart portion of the pressurising apparatus and the sealing nipple is produced at an auxiliary sealing surface of the sealing nipple, which perform no function upon subsequent use on an internal combustion engine. As a result deformation or even damage which may occur at that auxiliary sealing surface because of the very high contact pressure involved does not play any part in no operation of the arrangement. When the sealing nipple is cl into position in the pressurising :)aratus, the main sealing surface of the sealing nipple, which produces the sealing connection upon being fitted to an internal combustion engine, either remains letely contact-free, or it is loaded at least to such a slight degree that it does not suffer frem deformation phenomena which would adversely affect subsequent functioning thereof.

By virtue of the fact that the sealing edge of the main sealing surface is deformed for the first time when first fitted to the internal combustion engine, even if the injection line has previously been put under pressure by means of a pressurising apparatus according to the invention, the union nut or a cap screw can be tightened with the usual level of torque and in particular the number of removal and refitting operations possible therewith remains unaltered.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawing in which:

Figure 1 shows part of a fuel injection line which in normal operation is pressed with its sealing nipple against a counterpart T' 4 - 1 4 portion of a Diesel engine, and Figure 2 shows the part of the fuel injection line of Figure 1 in the assembled condition with a pressurising apparatus according to the invention.

Referring to Figure 1 shown therein is one end of a fuel injection line 1 for an internal combustion engine, with a sealing nipple 3 which is formed by upsetting thereon. The other end (not shown) of the line can be of a corresponding configuration.

The sealing nipple 3 has a sealing cone 4 which is formed in the upsetting operation and which provides a main sealing surface 5 which to provide sealing integrity is pressed against a hollow-conical cooperating sealing surface 6, which has a conical angle of about 60', of a counterpart portion 7.

The counterpart portion 7 can be for example a component of an injection nozzle which is supplied with fuel from an injection pump (not shown) by way of the fuel injection line 1. The connection of the fuel injection line 1 to the above-mentioned injection pump can be of a corresponding design configuration.

The rearward supp6rt surface of the sealing nipple 3 is in the shape of a spherical seg-nent 8 and serves for bearing against a hollow- conical surface 9 of a union or cap nut 10. For sealingly pressing the main sealing surface 5 of the sealing nipple 3 against the co-operating sealing surface 6 of the counterpart portion 7, the union nut 10 is screwed on to a male screwthread 11 on the counterpart portion 7 in the usual way.

The hollow-conical co-operating sealing surface 6 has a somewhat larger opening angle than the sealing cone 4 so that contact between the two surfaces is certain to occur at the small diameter of the sealing cone 4. In that situation the sealing edge 12 with which the main sealing surface 5 passes into the end face 14 of the sealing cone 4 adapts to the hollow-conical co-operating sealing surface 6 of the counterpart portion 7, by virtue of plastic defolTmtion. In each fresh fitting operation the deformation which is already present at the sealing edge 12 must be increased, which is effected by the union nut 10 being tightened with increasingly higher levels of torque.

if now before it is first f itted to a motor vehicle the injection line 1 is to be pressurised for example for test purposes at 1 a very high pressure which can be two to three times the normal operating pressure, for that purpose it has to be pressure-tightly connected to a pressurising apparatus of which Figure 2 shows only a counterpart portion 71 corresponding to the counterpart portion indicated at 7 in Figure 1. Because of the above-mentioned high operating pressures, the union nut 101 which serves to press the sealing nipple 3 against the counterpart portion 71 of the pressurising apparatus has to be tightened at a particularly high level of torque. If now the sealing surface 5 of the sealing cone 4 were also to be used here for making the sealing connection to the counterpart portion 71, considerable deformation of the sealing edge 12 would already occur in this pressurising operation, so that the sealing edge 12 would be only still limitedly suitable for regular use on the Diesel engine and under some circumstances would no longer be suitable at all for that purpose.

In order to avoid this the hollow-conical surface 61 which is also provided on the counterpart portion 71 is of such a configuration that it does not come into contact with the main sealing surface 5 and in particular the sealing edge 12 of the sealing cone 4.

Instead, an intermediate portion 18 is fitted into a cylindrical recess 16 in the counterpart portion 7, the cylindrical recess 16 adjoining the hollow-conical surface 6' in the axial direction. In the assembled condition the intermediate portion 18 has an end face 20 which is disposed in opposite and substantially parallel relationship to the end face 14 of the sealing cone 4. Provided on the end face 20 of the intermediate portion 18 is an annular bead or ridge 22 which concentrically surrounds a duct 24 which in the interior of the intermediate portion 18 coaxially extends the internal cavity in the fuel injection.line 1.

The sealing bead or ridge 22 projects beyond the end face 20 in the axial direction towards the sealing nipple 3 to such a distance that in the assembled condition it comes into sealing engagement with the end face 14 thereof.

In that way it is possible for the union nut 10 1 to be tightened on the male screwthread 1-11 of the counterpart portion 7 with such a high level of torque that the connection between the annular sealing bead or ridge 22 which functions here as the co-operating sealing 6 surface of the counterpart portl On V, and the end face 14 which serves as an auxiliary sealing surface of the sealing nipple 3, can withstand even the very high pressures to which the fuel injection line 1 is subjected in the pressurising apparatus.

Any deformation of the end face 14 which may occur in that situation does not have any adverse effect on later use of the injection line 1 on the Diesel engine because there the main sealing surface 5 which has remained completely contact-free in the pressurising operation, or the sealing edge 12 which is also not yet deformed, become operative.

As can further be seen from Figure 2, formed on the end 25 of the intermediate portion 18, which is opposite to the end face 20, is a frustoconical surface 26 which, by virtue of the pressure applied to the annular bead or ridge 22 by the end face 14 of the sealing nipple 3 is pressed sealingly against a sealing edge 28 with which the bottom surface of the cylindrical recess 16 goes into a hollow-conical surface 30 of the counterpart portion 7', that surface then communicating with a duct 32 which extends it.

In principle it Wbuld also be possible for the intermediate portion 18 to be made in one piece with the counterpart portion 7. The illustrated construction however affords advantages from the production engineering point of view.

As an alternative to the illustrated embodiment, the end face 20 could also be completely flat and instead an annular bead or ridge, corresponding to the annular bead or ridge 22, could be provided on the end f ace 14 of the sealing nipple. As can be seen from Figure 1 such an annular bead would not cause any problems when the injection line 1 is used on an internal combustion engine.

The use. of. an auxiliary sealing surface according to the invention in relation to an operation of pressurising an injection line, prior to actual use on an internal combustion engine, is not restricted to the sealing nipple shape shown in the Figures. It is for example and in particular also possible when the main sealing surface 5 of the sealing nipple is for example not conical but is in the form of the surface of a spherical segment. Instead of a union nut, it is also possible to use a cap screw for pressing the sealing nipple against the counterpart portions 7 or 71 respectively.

7 It will be seen therefore that with the design of the pressurising apparatus and the injection fuel line according to the invention, in spite of the high pressures involved, an adverse effect on subsequent sealing of the sealing edge of the main sealing surface in normal operation is avoided.

It will be appreciated that the above-described embodiments of the apparatus and the fuel injection line have been described solely by way of exarple of the invention and that various modifications and alterations may be made therein without thereby departing frcm the scope of the invention as defined by the appended claims.

8

Claims

1. A pressurising apparatus for subjecting a fuel injection line having a sealing nipple at least at its one end for an internal combustion engine to an increased internal pressure outside normal operation, which sealing nipple includes a main sealing surface which in normal operation can be pressed against a co-operating sealing surface of a counterpart portion of the engine or the fuel purp respectively, the pressurising apparatus comprising a counterpart portion which includes a co-operating sealing surface of such a configuration and arrangenent that it comes into pressure-tight pressing engagenent with an auxiliary sealing surface of the sealing nipple so that when the sealing nipple is clamped into the pressurising apparatus the main sealing surface of the sealing nipple is not exposed to a deforming loading.

2. Apparatus according to claim 1 wherein for a sealing nipple whose main sealing surface is of a conical or spherical configuration and is defined by an end face extending transversely to the longitudinal axis of the fuel injection line, the co-operating sealing surface of the counterpart portion of the pressurising apparatus is of such a configuration that the end face of the sealing nipple serves as the auxiliary sealing surface.

3. Apparatus according to claim 2 wherein the pressure-tight connection between the counterpart portion of the pressurising apparatus and the sealing nipple is made by means of an annular bead.

4. Apparatus according to claim 3 wherein the annular bead is provided on the counterpart portion of the pressurising apparatus and is pressed against r-he substantially flat end face of the sealing nipple.

9

5. Apparatus according to claim 3 wherein the annular bead is provided on the end face of the sealing nipple and is pressed against a substantially flat co-operating sealing surface of the counterpart portion 7) of the pressurising apparatus.

6. A pressurising apparatus substantially as hereinbefore described with reference to the accanpanying drawing.

7. A fuel injection line for use with a pressurising apparatus according to one of the preceding claim, comprising at least one sealing nipple including a main sealing surface with which it is capable of being pressed sealingly during normal operation against a co-operating sealing surface of a counterpart portion of an internal combustion engine or a fuel pump, and an auxiliary sealing surface with which it is capable of being pressure -tightly pressed against a co-operating sealing surface of a counterpart portion of the pressurising apparatus so that the main sealing surface is not subjected to a deforming loading.

8. A fuel injection line substantially as hereinbefore described with reference to the acccffpanying drawing.