GB2224774A

GB2224774A - Die cast i.c. engine fuel injector and pressure regulator support manifold

Info

Publication number: GB2224774A
Application number: GB8921989A
Authority: GB
Inventors: Silverio Bonfiglioli; Rino Stagni
Original assignee: Weber SRL
Current assignee: Weber SRL
Priority date: 1988-09-30
Filing date: 1989-09-29
Publication date: 1990-05-16
Also published as: IT8853429V0; FR2637322A1; GB8921989D0; DE3932672A1; IT214868Z2

Abstract

Tho tubular element 15 defines an axial fuel supply bore 16, a series of projecting sleeves 17 which each define a seat 2 for an electromagnetic fuel injector and a projection 18 with a seat 19 for a pressure regulator. Blind holes 20, 21 in the projection 18 are machined through to the bore 16 to provide communication with the bore on either side of a cover (10, Fig.1). Other projections on the element 15 provide an inlet connector 35, an outlet connector (34, Figs. 2 and 12) and reinforced support means (32, Figs 2,7 and 11). The element 15 has external axial ribs 26. <IMAGE>

Description

A BLANK FOR PRODUCING A FUEL SUPPLY MANIFOLD FOR AN INTERNAL COMBUSTION ENGINE FUEL INJECTION SYSTEM The present invention relates to a blank for producing a fuel manifold for a fuel injection system of an internal combustion engine, which is adapted to supply the fuel under pressure to a plurality of electromagnetically actuated fuel metering and atomisation valves.

Manifolds of this type substantially comprise a duct which is in communication with a fuel pipe and with a pressure regulator device adapted to maintain substantially constant the pressure within the interior of the duct itself; the manifold further comprises a plurality of connectors each of which is in hydraulic communication with this duct and defines a seat for housing a fuel metering and atomisation valve.

Normally a manifold of this type is produced utilising sections of tube variously connected together, the connections normally being made by welding, which tube sections are adapted to form the duct and the first defined connectors; moreover, to such parts there are fixed flanges, tongues or similar members adapted to allow the connection of the manifold itself to the pressure regulator device and the fuel supply pipe, as well as for supporting the manifold on the air induction manifold of the engine.

Manifolds formed in the above indicated manner are rather expensive because of the large number of components of which they are composed and the operations which are necessary to connect the components together.

Moreover, they are of low reliability in use since they can easily be subject to leakage of fuel, in particular in correspondence with the connection zones between the various parts of the manifold: In fact the welding can be defective and, because of the high pressure of the fuel which circulates within the manifold itself, can easily result in fuel leakages.

Manifolds of this type are also known which are made from a metal blank made by a hot stamping operation from a billet; the thus obtained blank substantially comprises a bar from which project, normally in a direction perpendicular to the longitudinal axis of the bar itself, parts of various form adapted to form the connectors and the first mentioned tongues. These blanks are subsequently subject to mechanical machining operations and, in particular, are pierced in the direction of the longitudinal axis for the purpose of forming the fuel duct.Although such manifolds formed utilising the blank described are more reliable and less expensive than those made by connecting together several parts, they can still be subject to fuel leakages because of the porosity of the material of the blank, which is consequent on the billet stamping operation; moreover the manifold thus obtained is still expensive because of the great influence which the numerous mechanical machining operations have on the overall cost, which operations are necessary to obtain the completely finished manifold; in particular the longitudinal piercing of the blank takes a long time and requires special tooling because of the great axial length of the blank.

The object of the present invention is that of providing a blank for producing a fuel supply manifold of the type first indicated, with which it is possible to obtain a manifold free from the disadvantages which have been described, and which therefore will be of low cost and have a high reliability in use.

These objects are achieved by means of a blank for producing a fuel manifold for an internal combustion engine fuel injection system, the said manifold defining an axial duct for the fuel and a variety of seats for corresponding electromagnetically actuated fuel metering and atomisation valves which are in communication with the said duct, and a seat for a fuel pressure regulator device, characterised by the fact that it includes a tubular element defining an axial hole for the fuel, a series of first sleeves projecting laterally from the said tubular element each of which is in communication with the said axial hole and defines within it one of the said seats, a projection extending radially from one end of the said tubular element on which is formed a seat for the said pressure regulator device and a pair of blind holes having axes perpendicular to that of the said axial hole, the said blank being produced from molten metal material injected under pressure into a mould.

For a better understanding of the blank of the present invention a more detailed description of it will now be given by way of example with reference to the attached drawings, in which: Figure 1 schematically represents a fuel manifold in which the blank of the invention can be utilised; Figures 2 and 3 respectively represent a side view and a longitudinal section of the blank of the invention; Figures 4 to 6 represent sections of the blank taken on the lines IV-IV, V-V and VI-VI respectively; Figure 7 is a detailed view of the blank of Figure 1; Figure 8 is a longitudinal section of the blank of Figure 3 on which have been performed some simple mechanical machining operations; Figures 9 and 10 are sections of the blank on which the said operations have been effected, taken on the lines IX-IX and X-X respectively;;l Figure 11 is a view of the detail shown in Figure 7 of after the said operations have been performed; and Figure 12 is a section of the blank on which the said operations have been performed, taken on the line XII-XII.

The blank of the invention is capable of forming a fuel supply manifold of the type schematically represented in Figure 1, which comprises substantially an axial duct 1 for the fuel and a plurality of seats 2 for corresponding electromagnetically actuated fuel metering and atomisation valves, indicated 3; the duct 1 communicates with a fuel inlet hole 4 and with a fuel outlet hole 5 which is connected to a pressure regulator 6 fixed to a suitable seat of the manifold itself. The manifold further includes a chamber 7 coaxial with the duct 1 and defined by the wall part 8 of the duct 1 and by a pair of small covers 9 and 10 inserted into the wall itself; the chamber 7 communicates through the hole 11 with the pressure regulator device 6 and through a hole 12 with the discharge.

In a manifold of this type the fuel supplied to the hole 4 arrives at the metering and atomisation valves 3 and is maintained at a substantially constant pressure by the pressure regulator 6: This is able to cause a part of the fuel to flow back through the hole 11, the chamber 7 and the duct 12 when the pressure within the duct 1 exceeds a predetermined value.

The blank of the invention is shown in Figures 2 and 3 and comprises substantially a tubular element 15 defining an axial hole 16 for the fuel and a series of first sleeves projecting laterally from the said tubular element, each of which communicates with the axial hole 16 and defines one of the seats 2 (Figure 1) for a corresponding fuel metering and atomisation valve 3.

The blank further includes a projection 18 extending radially from one end of the tubular element 15 and on which is formed a seat 19 for the pressure regulator device 6 (Figure 1), as well as a pair of blind holes 20 and 21 having axes perpendicular to that of the hole 16.

The blank with the parts just described is made in one piece from molten metal material injected under pressure into a mould; this die-casting moulding operation is performed utilising moulds and machines well known in the scope of this technology.

According to the invention the axial hole 16 of the tubular element 15 includes two coaxial conical hole sections 16a, 16b converging towards the central part of the blank; in this way the smaller diameter of the sections is located in correspondence with the central portion indicated 22.

The tubular element 15 has a wall 25 having a substantially constant thickness over the whole of the length of the conical hole sections 16a, 16b as is visible from the section of Figure 3.

Conveniently the cone angle of each of the said conical sections lies between 0.4 and 0.8%. Further the ratio between the thickness of the wall 25 and the axial length of the wall itself lies between 0.5 and 1.5%.

The wall 25 includes a plurality of outer ribs (four in the case of the illustrated embodimer.t) each of which projects radially from the outer surface of the wall and has an axis parallel to that of the hole 16; the radial height of each rib increases gradually from each end of the hole sections 16a and 16b towards the central part of the blank (section 22) in such a way that the outer surfaces of the said ribs are substantially tangential to a cylindrical surface having an axis coincident with the axis of the axial hole 16.

Conveniently, as is clearly seen from Figures 2 and 3, the axis of each of the sleeves 17 forms an angle less than 900 with the axis of the axial hole 16; the axial hole 16 is in tommunication with each of the seats 2 through a short hole having a diameter less than that of the seats.

The axial hole 16 comprises at least one cylindrical hole section 16c formed in the end of the tubular element from which the projection 18 extends. The diameter of this hole section is greater than the maximum diameter of the contiguous conical hole section 16a in such a way as to define between the two hole sections an annular shoulder 27 positioned between the two blind holes 20 and 21 as is clearly seen from the section Figure 3. Moreover, a cylindrical seat of greater diameter than that of the hole section 16a, and indicated 28 is positioned at the very end of the tubular element.

The manifold further includes a pair of flat tongues 32 projecting radially from the outer surface of the tubular element 15 (Figure 2), each of which forms an angle lying between 00 and 900 with the axis of the axial hole 16; each of these is reinforced with a pair of triangular ribs indicated 33 and visible in Figure 7, which are disposed in planes parallel to the axis of the axial hole 16 as can be seen from Figure 2.

Finally, the blank includes a pair of second sleeves 34 (Figure 2) and 35 (Figure 3) which have axes perpendicular to the axis of the axial hole 16; the first is in communication with the cylindrical hole section 16; the other is in communication with the end of the conical hole section 16b.

The blank described allows a fuel manifold to be obtained of the type schematically illustrated in Figure 1. In fact, on the blank thus formed it is sufficient to perform a few simple machining operations such as those necessary for completing the piercing of the blind holes 20 and 21 (Figure 3) in such a way as to put these into communication first with the hole section 16c and second with the hole section 16a as has been shown in the sectional view of Figure 8. Moreover the inner holes within the connectors 34 and 35 can be threaded as has been shown in the sectional view of Figure 12; finally, the seat 2 can be tapered towards the outside with a bevel 36 (Figure 8), while in each tongue 32 can be formed a hole 37 (Figure 11). The blank obtained at the end of these further operations can be utilised to produce a manifold as shown in the diagram of Figure 1.

In fact, against the shoulder 27 (Figure 3) and within the seat 28 can be disposed small covers 10 and 9 (Figure 1) to define the chambers 7; moreover the left hand end of the hole 16 can be closed by a further small cover 38; finally the fuel metering and atomisation valves can be housed in the seats 2 and the pressure regulator device 6 fixed to the corresponding seat 19 of the projection 18.

In use the fuel under pressure coming from the feed hole 4 supplies the fuel metering and atomisation valves 3 and is maintained under substantially constant pressure by the action of the pressure regulator 6: In fact, when this pressure exceeds a predetermined value a part of the fuel will be discharged through a hole 11 and the chamber 7 to the discharge hole 12 in this way regaining the correct working pressure.

The blank which has been described can be produced at low cost utilising die-casting technology: This is possible both because of the form of the various parts of which the blank is composed, and because of the dimensions of some of these parts. In particular an easy extraction of the blank from the mould is possible because of the taper of the duct sections 16a and 16b; also the form and arrangement of the other parts make extraction of the blank from the associated mould possible. Also the constant thickness of the wall 25 and the ratio between this thickness and the length of the blank makes it possible significantly to reduce the shrinkage during the forming operation and to have a significant homogeneity off the material.

It has further been found that internal porosity of the body of the blank is entirely absent and therefore there is no loss of fuel in use, even with very narrow thickness of the wall 25. Because of the shape of the various parts, there is no localised shrinkage which would tend to alter the shape of the blank with respect to the theoretically designed shape.

It is apparent that the embodiment of the blank described can have modifications and variations introduced thereto without departing from the ambit of the invention.

Claims

1 A blank for producing a fuel manifold for an internal combustion engine fuel injection system, the said manifold defining an axial duct for the fuel and a plurality of seats for corresponding electromagnetically actuated fuel metering and atomisation valves which are in communication with the said duct and a seat for a fuel pressure regulating device , characterised by the fact that it comprises a tubular element defining an axial hole for the fuel, a series of first sleeves projecting laterally from the said tubular element, each of which is in communication with the said axial hole and defines within its interior one of the said ses a projection extending radially from one end of the said tubular element on which a seat for the said pressure regulator device is formed and a pair of blind holes having axes perpendicular to that of the said axial hole, the said blank being made from molten metal materiel injected under pressute into a mould.

2. A blank according to Claim 1, characterised by the fact that the said axial hole of the said tubular element includes two conical hole sections tapering towards the central part of the blank, the said tubular element having a wall with a substantially constant thickness over the whole of the length of the said conical hole portions.

3. A blank according to Claim 2, characterised by the fact that the cone angle of each of the conical hole portions lies between 0.4 and 0.8%.

4. A blank according to Claim 2 or Claim 3, characterised by the fact that the ratio between the thickness of each of the said walls and the axial length of the wall itself lies between 0.5 and 1.5%.

5. A blank according to any of claims 2 to 4, characterised by the fact that the said wall includes a plurality of outer ribs projecting radially from the outer surface of the wall itself and having axes parallel to that of the said axial hole, the radial height of each of the said ribs gradually increasing from each end of the said hole section towards the central part of the blank in such a way that the outer surfaces of the said ribs are substantially tangential to a cylindrical surface having ar axis coincident with the axis of the said axial hole.

6. A blank according to any preceding claim, characterised by the fact that the axis of each of the said sleeves forms an angle less than 900 with the axis of the said axial hole , the said axial hole including at least one cylindrical hole portion formed in the said end of the tubular element from which the said projection extends.

7. A blank according to claim 6, characterised by the fact that the diameter of the said cylindrical hole portion is greater than the maximum diameter of the conical hole portion which communicates with it, in such a way as to form between the said two sections an annular shoulder positioned between the said blind holes.

8. A blank according to any preceding claim, characterised by the fact that it includes a pair of flat tongues projecting radially from the outer surface of the said tubular element and each of which forms an angle lying between 0 and 900 with the axis of the said axial hole, each of the said tongues being reinforced by a pair of ribs of triangular form and disposed in planes parallel to the axis of the said axial hole.

9. A blank according to any preceding claim, characterised by the fact that it includes a pair of second sleeves having axes perpendicular to the axis of the said axial hole, one of which is in communication with the said cylindrical portion and the other of which is in communication with one of the said conical hole portions.

10. A blank for producing a fuel supply manifold for an internal combustion fuel injection system, substantially as described and illustrated in the attached drawings.