GB2240137A

GB2240137A - I.c. engine fuel injector nozzle

Info

Publication number: GB2240137A
Application number: GB9100808A
Authority: GB
Inventors: Silvestro Maurizio Di; Francesco Morini
Original assignee: Weber SRL
Current assignee: Weber SRL
Priority date: 1990-01-17
Filing date: 1991-01-15
Publication date: 1991-07-24
Also published as: FR2657124A1; IT9052823V0; FR2657124B1; GB9100808D0; IT9052823U1; DE4100457A1; IT223984Z2

Abstract

One or more orifices 6 direct fuel jets on to 2 tubular nozzle surface in order to atomise the fuel. The nozzle may be formed of two metal parts 31, 32 connected by laser beam welding. <IMAGE>

Description

:2:2 -Q C) X 3 77 INTERNAL COMBUSTION ENGINE SUPPLY DEVICE VALVE The

present invention relates to an internal combustion engine supply device valve featuring a nozzle designed to enable a substantial improvement in fuel atomization. Known valves of the aforementioned type comprise a nozzle in which are formed one or more fuel injection orifices supplying the engine. Correct operation of the engine is also known to depend on the extent to which the fuel is atomized.

The aim of the present invention is to provide a valve featuring a nozzle designed to improve fuel atomization as compared with known nozzles.

With this aim in view, according to the present invention. there is provided a fuel metering and atomizing valve for an internal combustion engine supply device, said valve comprising a plunger and a nozzle, said plunger acting on the base wall of said nozzle; characterised by the fact that, inside said nozzle. there are formed at least one orifice, through which a jet of fuel flows. and a surface on to which said jet is directed for effectively atomizing the fuel.

A preferred non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:

Fig.1 shows a partially sectioned view of a valve in accordance with the teachings of the present invention; Fig.2 shows a larger-scale section of a component on the Fig.1 valve; Fig.3 shows a section of a further embodiment of the Fig.2 component.

Number 1 in Fig.1 indicates a fuel metering and atomizing valve of a known internal combustion engine supply device 2 (a section of only part of which is shown). Valve 1 comprises a substantially tubular. in particular, an inverted-cup-shaped nozzle 3. which may be made of metal or plastic. Nozzle 3 comprises a cylindrical wall 4 and a top base wall 5 presenting, in the embodiment shown. two injection orifices 6 of the same diameter.

Device 2 comprises a body 7 supporting nozzle 3 at the bottom and which presents an axial hole 8 along which slides a plunger 9. In use. the bottom edge 11 of body 7 is turned inwards to act as a shoulder for an annular flange 12 extending from lateral wall 4 just below base wall 5 which,, by means of a washer 13,, is thus pressed towards an inner shoulder 14 formed along hole 8. In use, plunger 9 is known to be raised. against the action of spring means. by a ferromagnetic core, energized by an electric coil 15. attracting an anchor integral with plunger 9. Plunger 9 comprises a tubular rod 16. the bottom end of which is fitted with a truncated-cone-shaped head 17. Inside rod 16. the fuel flows down to the bottom end and, through radial holes 18, into a chamber 21 defined by the inside of hole 8 at washer 13. Head 17 presents a flat bottom face which. at a given operating stage, closes the top of a prechamber 22 formed in wall 5 of nozzle 3.

As shown in Fig.2, in the bottom wall of prechamber 22 in wall 5 of nozzle 3. there originate said injection orifices 6 by which fuel is supplied to the vehicle engine. Said orifices 6 provide, at the same time. for determining fuel flow and distributing the fuel jet, and are formed along axes diverging equally in relation to the longitudinal axis of nozzle 3. Said longitudinal axis and the axes of orifices 6 all lie in the same plane.

As shown in Fig.2. lateral wall 4 of nozzle 3 presents a top portion 25, close to wall 5, having a constant inside diameter; and a bottom portion 26 longer than portion 25 and having a diameter increasing gradually to the bottom end of nozzle 3. In particular, portion 26 is truncated-coneshaped. with a top inside diameter equal to that of portion 25. By appropriately calculating the angle of the orifice 6 axes in relation to the longitudinal axis of nozzle 3. and the increase in the inside diameter of portion 26 in relation to its length, the fuel jets originating from orifices 6 are directed on to the inner wall of portion 26 of nozzle 3,, the:-. impact of which provides for breaking said jets and so- substantially improving atomization of the fuel.

As shown schematically in Fig.2. the jet originating from orifices 6 is 2 substantially cylindrical and, upon impact, is deflected towards the longitudinal axis of nozzle 3 and tends to flare out in relation to its central core. Upon impact, in fact. the peripheral particles of the jet undergo a greater reduction inspeed than the central core, and therefore tend to flare out in relation to the central core, thus producing a fanshaped jet. Laboratory tests have shown that a difference of 7 between the angle a defined between the cylindrical jets originating from orifices 6 and the angle B defined between the central cores subsequent to impact is sufficient to achieve a high degree of fuel atomization.

Nozzle 3 in Fig.3 differs from that of Fig.2 by consisting of two coaxial metal parts 31 and 32 welded integral with each other, preferably by means of a laser weld 51. The overall design of nozzle 3 in Fig.3 is the same as that of Fig.2. so that certain parts are indicated using the same numbering system. Part 31 presents a cylindrical lateral wall 33 and a top base wall 34 in which orifices 6 and prechamber 22 are formed. Wall 33 presents a constant inside diameter. and flange 12 extending from its outer surface. The outer surface of the free end of wall 33 presents an annular recess 35 defining an outer annular shoulder 36 and an end portion 37 having a constant. smaller outside diameter. Part 32 presents two coaxial portions 38 and 41. portion 38 being short with a constant inside diameter, and portion 41. like portion 26 of nozzle 3 in Fig.2. presenting an inside diameter increasing gradually to the bottom end of nozzle 3. The inner surface of the free end of portion 38 presents an annular recess 42 defining an annular inner shoulder 43 and an end portion 44 having a constant, larger inside diameter. Portion 44 engages recess 35 and contacts shoulder 36, while portion 37 engages recess 42 and contacts shoulder 43. The outer surface of portion 44 presents an annular groove 45 which acts as a reference point for the laser beam during welding. The heat produced by a laser beam provides for melting the mating surfaces on to which it is directed, in this particular case,' the outer surface of portion 37 and the inner surface of portion 44. By virtue of the shape of the parts for welding and the provision of reference points. welding may also be performed automatically. Nozzle 3 in Fig.3 naturally operates in the same way as that of Fig.2.

The advantages of the present invention will be clear from the foregoing description.

In particular. it provides, inside nozzle 3. for directing the jet from injection orifices 6 on to an impact surface. thus providing, as already shown, for improved fuel atomization. Moreover, nozzle 3 is both,cheap and easy to produce.

The two-part design of nozzle 3 in Fig.3 enables a, number of nozzles to be manufactured with a common base (part 31), the impact surface of each nozzle presenting a different taper and. therefore, providing for a different degree of fuel atomization. That is to say. a common part 31 may be provided for a number of nozzles 3 and, depending on the required degree of atomization, welded to a part 32 having an appropriately tapered impact surface.

To those skilled in the art it will be clear that changes may be made to valve 1 as described and illustrated herein without, however, departing from the scope of the present invention.

For example. nozzle 3 may present one or more than two injection orifices, providing impact means are provided for the jet originating from the same; the angle of the injection orifices and the length of portion 26 or part 32 may be other than as shown herein; in place of orifices 6, nozzle 3 may be provided with a first calibrating orifice and, downstream from this. two or more distributing orifices from which fuel jets are directed on to a wall inside nozzle 3; finally, parts 31 and 32 may be welded by other than the laser welding technique.

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Claims

1) - A fuel metering and atomizing valve for an internal combustion engine supply device (2), said valve comprising a plunger (9) and a nozzle (3), said plunger (9) acting on the base wall (5, 34) of said nozzle (3); characterised by the fact that, inside said nozzle (3), there are formed at least one orifice (6), through which a jet of fuel flows. and a surface on to which said jet is directed for effectively atomizing the fuel.

2) - A valve as claimed in Claim 1, characterised by the fact that said orifice (6) is formed in said base wall (5, 34), and said impact surface is defined on the inner face of a substantially tubular lateral wall (4, 41) of said nozzle (3).

3) - A valve as claimed in Claim 2, characterised by the fact that said base wall (5, 34) presents at least two said orifices (6) which provide at the same time for determining fuel flow and distribution of said fuel jet. 4) - A valve as claimed in Claim 3, characterised by the fact that said orifices (6) are formed along axes diverging equally in relation to the longitudinal axis of said nozzle (3); said longitudinal axis and the axes of said orifices (6) lying in the same plane.

5) - A valve as claimed in at least one of the foregoing Claims from 2 to 4. characterised by the fact that said lateral wall (4) presents a top portion (25) next to said base wall (5) and having a constant inside - a diameter; and a bottom portion (26) longer than said- top.. portion (25) and having a diameter increasing gradually. to the bottom end of said nozzle (3); said impactsurface being defined on the inner face of said bottom portion (26). 6) - A valve as claimed in at least one of the foregoing A Claims from 2 to 4, characterised by the fact that said nozzle (3) is formed in two coaxial parts (31. 32) rendered integral with each other.

7) - A valve as claimed in Claim 6, characterised by the fact that said parts (31, 32) present respective end portions (37, 44) welded integral with each other via a laser beam weld (51).

8) - A valve as claimed in Claim 7. characterised by the fact that one of said end portions (37. 44) presents an annular groove (45) constituting a welding reference point.

9) - A valve as claimed in at least one of the foregoing Claims from 6 to 8, characterised by the fact that said first part (31) presents a cylindrical lateral wall (33) of constant inside diameter and said base wall (34); and said second part (32) presents two coaxial portions (38. 41), the first (38) being short with a constant inside diameter. and the second (41) constituting said lateral wall (41) having an inner face increasing gradually in diameter to the bottom end of said nozzle (3).

10) - A valve as claimed in Claim 9, characterised by the fact that the outer surface of the free end of said j ' lateral wall (33) of said first part (31) presents a first annular recess (35) defining an outer shoulder (36) and respective said end portion (37) of constant outside diameter; and the inner surface of the free end of said first portion (38) of said second part (32) presents a second annular recess (42) defining an inner shoulder (43) and respective said end portion (44) of constant inside diameter; said end portion (44) of said second part (32) engaging said first recess (35) and contacting said outer shoulder (36), and said end portion (37) of said first part (31) engaging said second recess (42) and contacting said inner shoulder (43).

11) An internal combustion engine fuel metering and atomizing valve, substantially as described and illustrated herein with reference to the accompanying drawings.

Pubhshed 1991 atThe Patent Office. St2te House. 66/71 High Holborn, L4ondunWC I R4'1?- Further copies m2y be obtained from Sales Branch, Unit 6, Nine Mile Point, Cwmficlinfach, Cross Keys, Ncwport. NPI 7RZ. Printed by Multiplex techniques ltd, St Mary Cray, Kent.