EP3636915A1

EP3636915A1 - Fuel injection assembly for an internal combustion engine

Info

Publication number: EP3636915A1
Application number: EP18199558.0A
Authority: EP
Inventors: Giandomenico Serra; Andrea Puccini; Marco Pasquali
Original assignee: Continental Automotive GmbH
Current assignee: Vitesco Technologies GmbH
Priority date: 2018-10-10
Filing date: 2018-10-10
Publication date: 2020-04-15

Abstract

A fuel injection assembly for an internal combustion engine is provided that includes an elongate fuel injector (2) having a longitudinal axis (4) having a fuel inlet (6) at one axial end of the fuel injector (2) and a fuel outlet (8) at the axially opposite end. The fuel injector (2) is located in an injector cup (10) adapted to be secured to the engine. The fuel injector (2) has an overmoulding (16) having two opposed faces (30) thereon. The injector cup (10) has an extending fork element (28) with two spaced tines (32) adapted to engage the two faces (30) therebetween to secure the injector (2) rotationally with respect to the engine.

Description

The present disclosure relates to a fuel injection assembly for an internal combustion engine, particularly but not exclusively, for a gasoline direct injection internal combustion engine.
Fuel injection assemblies are widely used for injecting fuel into an internal combustion engine, in one form having an injector for each cylinder of a multi-cylinder engine in which the fuel is supplied from a reservoir in the form of a fuel rail, also known as a common rail to which each of the injectors is connected. In known systems the injectors are secured directly to a bore in the cylinder head of the engine to project into the combustion chamber. Such arrangements have a disadvantage in that noise generated by the injection and combustion process is transmitted through the engine to the exterior. In order to reduce noise transmission one known solution is to isolate the injector from direct mechanical connection with the engine. One solution to this problem is to suspend the injector in a fuel rail injector cup which is itself secured to the fuel rail and the engine. In this way there is no direct mechanical coupling between the injector and the engine components.
A problem arises in that it possible for the fuel injector to pivot about the axis of the bore in the cylinder head or the injector cup during assembly or during use due to the vibrations to which the engine and fuel injectors are subjected. The fuel injector should be precisely positioned angularly relative to the injector cup so that the fuel injector fuel output is in the correct position relative to the combustion chamber to achieve the required fuel injection spray pattern into the combustion chamber. In some arrangements, such as that disclosed in WO 2015/135732 , this is achieved by means of a further component known as an indexing clip. US Patent No. 6, 651, 628 discloses an arrangement having a projection on the fuel injector over-moulding which engages in a recess in the engine housing.
The present disclosure seeks to provide a fuel injection assembly which is easier and quicker to assemble, whilst ensuring the correct positioning of the fuel injection spray.
According to the present disclosure there is provided a fuel injection assembly for an internal combustion engine. The fuel injection assembly comprises an elongate fuel injector having a longitudinal axis and having a fuel inlet at one axial end of the fuel injector and a fuel outlet at the axially opposite end, the fuel injector being located in an injector cup adapted to be secured to the engine. The fuel injector has bonded thereto an overmoulding having two opposed faces thereon. The injector cup has an extending fork element with two spaced tines adapted to engage the two faces therebetween to secure the injector rotationally with respect to the engine.
The fuel injector is indexed in the engine by engagement of the fork element on the injector cup with the overmoulding, in particular the tines or protruding arms of the fork element with two opposed faces on the overmoulding. "Indexed" refers to the angular orientation of the fuel injector with respect to the engine and more particular, with respect to the combustion chamber. With the proper indexing provided by the fork element and overmoulding, the correct spray pattern of the fuel injector in the combustion chamber can be guaranteed.
The injector cup and extending fork element can be easily formed. The tines of the fork element can be easily engaged with the opposed faces on the overmoulding so that assembly time and costs are reduced. Additionally, the use of opposed faces rather than protrusions avoids the possibility of breakage or damage of the protrusions and improves the reliability of the assembly process .
In a preferred embodiment, the fork element is formed integrally with the injector cup. This avoids the need to assembly a separate piece and also assists in achieving the correct indexing. Alternatively, the forked element may be provided as a separate piece that is attached to the injector cup.
In another embodiment, the two opposed faces are formed on a rib projecting from the overmoulding body. This form is useful for more simply producing the opposed faces on the overmoulding.
In an embodiment, the fork element engages the overmoulding with an interference fit in order to secure the fuel injector rotationally fast or fixed with respect to the engine. An interference fit may be used in installations where a high degree of precision in the indexing is desired.
In some embodiments, the gap between the tines and opposed faces is larger to facilitate easier assembly. This embodiment may be useful if such precise indexing is of less importance than the ease of assembly.
In an embodiment, the tines of the fork element have an outwardly chamfered edge at their extremity to facilitate assembly of the injector cup onto the overmoulding.
Preferred embodiments will now be described by way of example with reference to the drawings, in which:-

Figure 1 shows a sectional side view of a fuel injector assembly along the line B-B of Figure 2,
Figure 2 shows a cross-section of the fuel injector assembly of Figure 1 along the axis A-A of Figure 1
Figure 3 shows a perspective view of the fuel injector assembly shown in Figures 1 and 2, and
Figure 4 shows a perspective view of the injector cup and fuel injector.

Referring now to Figures 1 and 2, Figure 2 in particular illustrates schematically a fuel injector 2 for a fuel injector assembly for an internal combustion engine. The fuel injector 2 has an elongate body having a longitudinal axis 4 having a fuel inlet 6 at one end and a fuel outlet 8 at the axially opposite end. In the installed condition the fuel outlet 8 is in fluid communication with a combustion chamber of an internal combustion for direct injection of the fuel into the combustion chamber. In alternative arrangements, the fuel outlet 8 is in fluid communication with an engine inlet manifold through which fuel can be injected for a plurality of cylinders.
In a multicylinder engine, a fuel injector 2 is supplied for each cylinder of the engine and fuel to the cylinders is provided through a common rail (not shown) comprising a fuel reservoir having a plurality of spaced fuel outlets, one for each fuel injector.
The fuel injector 2 is located in an injector cup 10, shown in greater detail in Figure 3, which, in this embodiment, is secured to a fuel feed pipe 12 leading to a fuel reservoir in the form of a fuel rail (not shown) for a multicylinder engine, although the present disclosure is equally applicable to single cylinder engines. The fuel feed pipe 12 and hence the injector cup 10 is secured to the engine by a mount 14.
The fuel injector 2 has bonded thereto an over-moulding 16 which serves to secure the fuel injector 2 to the engine in the correct location to ensure that fuel spray from the fuel outlet 8 is directed into the combustion chamber in precisely the desired direction and position.
The injector cup 10 has a fork element 28 that is integrally formed with the injector cup. The fork element 28 extends downwardly parallel to but spaced from the axis of the fuel injector 2. At its outer, free end, the fork element 28 has a pair of spaced, depending arms or tines 30 which engage with the injector overmoulding 16 to fix the rotational position of the fuel injector 2 with respect to the engine..
Figure 3 shows a perspective view of the fuel injector assembly and shows the tines 30 engaging over the over moulding 16 and Figure 4 shows a perspective schematic view of the injector cup with the integrated the fork element and the injector with the overmoulding.
Referring now to Figures 3 and 4, there is shown a perspective view of the injector cup 10 illustrated in section has a generally cylindrical main body 16 open at its lower end to receive the inlet end 6 of the injector 2. As shown in Figure 3, the injector cup 10 has a radially outwardly extending flange 26 at the main body 18 at the lower end of the injector cup 10 which is curved at its junction with the main body to form an enlarged entry to facilitate entry of the injector inlet 6 into the injector cup 10.
At its upper end, the injector cup 10 has a spigot 22 of reduced diameter which is secured in the feed pipe 12. The spigot 22 has a hole or an orifice 24 to provide fluid communication from the feed pipe 12 through the injector cup 10 into the inlet 6 of the fuel injector to provide a fluid communication from the fuel reservoir to the injector fuel outlet 8.
The injector cup 10 has a fork element 28 integrally formed therewith which extends downwardly parallel to but spaced from the axis of the fuel injector 2. At its outer, free end, the fork element 28 has a pair of spaced, depending arms or tines 30 which engage with an interference fit on respective ones of two opposed faces 32 of the injector overmoulding. The arms form a U-shape which engages with the injector overmoulding. In this embodiment, the tines 30 engage on opposed faces of a rib extending from the main body of the over moulding.
By this means, the injector cup 10, which is secured against movement relative to the engine, locates the fuel injector so as to prevent movement of the injector in a rotational manner. In this way, the location of the outlet 8 of the fuel injector 2 is maintained in the correct position for the fuel spray on injection to be directed accurately in the desired direction and position in the combustion chamber.
In an alternative construction, the tines 30 engage over the main body of the over moulding 16 itself.
The outer extremities of the tines 30 may have on their facing surfaces a chamfer to facilitate the engagement of the fork element with the over moulding 16.
In the illustrated embodiment, the injector cup 10 together with the integrally formed fork element 28 is formed of a metal such as stainless steel and the over moulding 16 is formed of a plastics moulding material but other materials may be used. Although described as being integrally formed with the injector cup 10, it is possible for the indexing fork element 28 to be a separate component secured to the injector cup by brazing or other bonding method.
The degree of the interference fit between the fork element 28 and the over moulding 16 depends upon external requirements of the particular installation since the higher the force of the interference fit, the more precise the alignment between the injector cup and the over moulding 16 can be achieved and maintained. On the other hand, if the force of the interference fit is low, or non-existent, assembly can be much easier and faster.
Another advantage is that the two faces 32 engaged by the indexing fork element 28 can be part of the standard shape of the over moulding 16, thus obviating the need for a specially shaped over moulding and which also avoids the necessity to provide a plastic protrusion from the moulding which could provide a potential source of component failure.

Reference list

2: Fuel injector
4: Axis
6: Fuel inlet
8: Fuel outlet
10: Injector cup
12: Fuel feed pipe
14: Mount
16: Overmoulding
18: Main body
20: Enlarged entry
22: Spigot
24: Orifice
26: Flange
28: Fork element
30: Tine
32: Opposed faces

Claims

A fuel injection assembly for an internal combustion engine, the fuel injection assembly comprising an elongate fuel injector (2) having a longitudinal axis (4) and having a fuel inlet (6) at one axial end of the fuel injector (2) and a fuel outlet (8) at an axially opposite end, the fuel injector (2) being located in an injector cup (10) adapted to be secured to the engine, wherein the fuel injector (2)has an overmoulding (16) having two opposed faces (30) thereon, the injector cup (10) having an extending fork element (28) with two spaced tines (32) adapted to engage the two faces (30) therebetween to secure the injector (2) rotationally with respect to the engine.
A fuel injection assembly according to claim 1, wherein the fork element (28) is formed integrally with the injector cup (2) .
A fuel injection assembly according to claim 1 or 2, wherein the two faces (30) are formed on a rib projecting from the overmoulding (16).
A fuel injection assembly according to anyone of the preceding claims, wherein the fork element (28) engages the overmoulding (16) with an interference fit.
A fuel injection assembly according to any one of the preceding claims, wherein the tines (32) of the fork element (28) have an inwardly facing chamfered edge at their extremity to facilitate assembly of the injector cup onto the overmoulding.
A fuel injection assembly according to any one of the preceding claims, wherein the injector cup (10) has a radially extending flange (26) extending from the lower end thereof and curved at its junction with the main body (18) of the injector cup (10) to form an enlarged entry (20).