NOZZLE TO SUPPLY LIQUID / GAS MIXTURE
Pwmpr-Technical The present invention relates to a nozzle for supplying a liquid / gas mixture, for example, to the intake manifold or to the internal combustion chamber. The nozzle can be part of a fuel injection * for an engine, particularly but not exclusively when the injector produces a mixture and where a fine mist of fuel droplets enters a stream of air before entering a combustion chamber. Although the present invention will be described with respect to a preferred application of fuel injectors for internal combustion engines, it will be appreciated that it has applicability to any environment, where a liquid / gas mixture mixture is to be supplied in such a way that the adhesion of the liquid film at an exit from the nozzle will be improved in supply systems, whether continuous or discontinuous. It is known to create a liquid / gas mixture by supplying a generally cohesive sheet of a liquid in a stream of gas flowing through a passage, the gas acting to shear the liquid droplets away from the liquid sheet. Such a liquid / gas mixture has been found to have an average liquid droplet size smaller than that produced by supplying liquid under pressure through a nozzle to form a spray as many injectors of commonly available motor vehicles operate. A liquid / gas mixing apparatus which operates by shearing drops of liquid at a distance from a liquid sheet is disclosed in AU-A-51454/93 and which is incorporated herein by reference. Due to the very small size of the liquid droplets, the liquid / gas mixture produced by shearing liquid droplets from a liquid sheet using a gas stream can be delivered through a passage beyond the point at which the liquid is liquid. Shearing the sheet and out through a nozzle. If the nozzle has a simple continuous expansion zone leading to its exit, it has been found that such a nozzle supplying liquid / gas mixtures tends to adhere liquid and accumulate liquid on the internal surface of the expansion zone, and said liquid is pushed through the passage and out of the outlet as relatively large drops compared to the fine mist that enters the stream of gas that flows inside. the mouthpiece It would be desirable to eliminate or at least minimize such adhesion, the accumulation and supply of liquid droplets from the outlet of the nozzle. The present invention provides a nozzle for supplying a gas / liquid mixture, comprising: a body having a flow passage leading to an outlet; an expansion zone near the outlet and at least one discontinuity in the expansion zone, formed as an elongation extending in stages followed by a cylindrical portion of parallel sides extending towards the outlet, said discontinuity being adapted to reduce the adhesion of the liquid film in the output. Preferably, each discontinuity is substantially circumferential in degree. Preferably, said discontinuity is an elongation in the expansion zone stage. The expansion zone preferably has a plurality of elongations in stages. Preferably the flow passage also has a restriction or compression zone spaced upstream of the expansion zone. The restriction or compression zone is preferably a substantially convergent portion of the flow passage, and which leads to a throat portion that is intermediate to the restriction zone and to the expansion zone. The flow passage is preferably generally circular in cross section, the restriction zone being generally conical. The or each elongation is in the expansion zone is preferably in a shape of a circumferential edge having a first diameter, a radially outwardly extending surface, which is generally normal to the central axis of the flow passage, and an axially extending cylindrical surface having a second diameter, which is a predetermined amount greater than the first diameter , and which leads to the next elongation in adjacent or exit stages. In a specific embodiment, the intermediate throat portion has a diameter of about 4 mm, the axial cylindrical surface of a first stepwise elongation has a diameter of about 5 mm, and the axial cylindrical surface of the second and third step elongation has a diameter of approximately 6 mm and 7 mm, respectively. The restriction zone preferably converges from a diameter of about 10 mm to the diameter of 4 mm of the throat portion over an axial distance of about 5 mm. In addition, the throat portion preferably extends around 13 mm, the cylindrical surfaces of the first and second stepwise elongations extend approximately 3 mm in the axial direction, and the cylindrical surface of a terper. Stage elongation extends approximately 4 mm in the axial direction. A particularly preferred embodiment is formed by a plurality of axially aligned nozzles, according to the present invention, wherein the outlet of a nozzle is adapted to supply a liquid / gas mixture to a mixing nozzle and wherein the adjacent nozzles are separated by gas and / or liquid inspiration zones such that the gas and / or inspired liquid is adapted to mix with the liquid / gas mixture as it passes from the outlet of a nozzle - to the inlet of the next nozzle adjacent axially aligned. The number of nozzle stages separated by the inspiration zone may vary as desired. In use with the embodiments according to the disclosure in AU-A-51454/93 I have found that in the environment of internal combustion engines a minimum amount of pressurized air is required, to atomize a liquid fuel to a desired particle size. . In a prototype this has been established in at least 1% stoichiometric air at 100 psi. That pressurized air is forced through an injector to shear the droplets from a conical fuel blade with the resulting fuel / air mixture leaving by means of a supply nozzle according to one embodiment of the present invention. The addition of an air premix which is a minimum amount of air necessary (when combined with the primary air that effects a shearing action of the fuel inside the body of the injector) that facilitates a preparation of a quality premix for good combustion. The amount of premix air includes atomizing the air which is usually about 5% of the total t required of a stoichiometric mixture. With the further addition of vaporization air (tertiary air *) it is possible to vaporize the fuel and give additional premix to improve combustion. An air of vaporization is understood to mean the minimum amount of air needed (when combined with primary and secondary air) to vaporize the fuel and give the additional premix to improve combustion. Such a tertiary air can be inspired by the fuel / air mixture by means of a novel additional stage or by air inlets arranged radially on a ring extending past the outlet of the second outlet stage. Of course, as stated above, the number of nozzle stages can be varied as desired. I have found that a single or multiple nozzle arrangement according to the present invention not only minimizes fuel film adhesion but also creates good mixing and reduces speed and widens the fuel air mixture allowing entry of more air inside the mixture. A secondary air nozzle can be attached to an intake manifold of the internal combustion engine or used for the introduction of other fuels or both fuel and air. When used in the environment of a pressurized injector of the di-vulgar form in AU-A-51454/93 the efficiency of a nozzle of the present invention does not depend on a negative pressure generated by a motor which may be the case for said injectors aided with air. BRIEF DESCRIPTION OF THE DRAWINGS Preferred forms of the present invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a schematic longitudinal sectional view of a nozzle embodiment according to the present invention; Figure 2 is a schematic longitudinal view of the nozzle of Figure 1 • and a part of a known liquid / gas mixing apparatus; Figure 3 is a detailed schematic view of a portion of the nozzle of Figure 1 showing the gas / liquid mixture flow and the action of the gas stream on the liquid which has adhered to the surface of the zone of expansion; Fig. 4 is a sectional view of the general arrangement of an embodiment of an injector mounted in a two-stage nozzle array embodiment of the present invention;
Figure 5 is an enlarged view of a portion of the injector of Figure 4; Figure 6 schematically represents an injector nozzle arrangement of Figure 4 configured to provide direct injection into an input manifold of an internal combustion engine; Figure 7 is a sectional view of the nozzle and nozzle arrangement of Figure 4 mounted on an inlet manifold; and Figure 8 is a view similar to Figure 7, but showing the nozzle and nozzle arrangement mounted on an inlet manifold in an alternative to that of Figure 7. Best Mode for Carrying the Invention The drawings show an elongated nozzle 10 with a centrally extending passageway 11, a restriction or compression zone 12 at an entrance end 13 and an expansion zone 14 near the exit 15. The expansion zone 14 is in the form of a series of extensions in three stages 16, each of which defines circumferential discontinuities along the flow passage 11. Each arrangement in stages 16 has a circumferential edge 17, a radially outwardly extending surface 18, which is generally normal to the central axis of the nozzle 10, and an axially extending cylindrical surface 19 having a diameter that is a predetermined amount greater than that of its associated edge 17. The restriction zone 12 has a conical surface 20 that converges with the diameter of a throat portion 21 which is intermediate to the restriction zone 12 and to the expansion zone 13. Referring to the figure. 2, which shows the nozzle 10 mounted on a part 30 of a liquid / gas mixing apparatus which is generally disclosed in AU-A-51454/93 for the present invention. The mixing apparatus includes a liquid valve 31 that intermittently supplies a sheet of liquid projecting radially or conically outward in an annular flow passage 32. The mixing apparatus 30 has gas valves (not shown) is supplied a gas stream through the passage 32 at least from a time just before the liquid valve 31 opens and at least until a time just after the liquid valve 31 closes. The gas stream through passage 32 acts to shear liquid particles away from the liquid sheet producing a fine mist of liquid particles entering the gas stream. The liquid / gas mixture flows through the passage 32 of the mixing apparatus 30. The passage 32 communicates with the flow passage 11 of the nozzle 10 which is positioned downstream at the point at which the liquid particles are sheared to distance from. liquid sheet. The nozzle 10 defines the outlet for the mixing apparatus 30 for supplying the liquid / gas mixture, which may be a fuel / air mixture in the combustion chamber of an internal combustion engine (not shown). In use, the liquid / gas mixture enters the nozzle
and is decompressed through the restriction zone 12 before passing into the intermediate throat portion 21. This serves to accelerate the flow of gas and liquid particles. When the stream reaches the expansion zone 13, the liquid / gas mixture expands as each of the edges 17 passes and after that is supplied through the outlet 15. When the liquid droplets that have adhered to the Flow passage reaches the first 'edge 17, it is believed that the action of the gas stream passing over the discontinuity causes the accumulated liquid to be pulled out of the surface as relatively small particles, that is, having a particle size which is considerably less than if the accumulated liquid had been allowed to discharge from the expansion zone of the nozzle without such discontinuities. More particularly, the discontinuities defined by the elongations in stages 16 cause the gas stream (with the liquid droplets introduced) to flow and expand radially outwardly on and around the edges 17 producing turbulence adjacent to the radially projecting surface 18. It has been observed that the nozzle 10 of the embodiment of Figures 1-3 removes the adhering liquid from the expansion zone before it is delivered through the nozzle 15 as undesirably large liquid droplets., which are generally not able to 'be burned efficiently in a normal combustion cycle. This benefit is achieved if the liquid valve 31 and the gas valve (not shown) of the mixing apparatus 30 are opened / closed intermittently to produce intermittent gusts of liquid / gas mixture, or kept open to supply continuous flow. of the liquid / gas mixture. In the general arrangement view of the embodiment of Figure 4 there is shown an injection and nozzle combination 40 comprising an injector operated by solenoid 41 fitted with a two stage nozzle arrangement.42. The injector 41 comprises a solenoid cover 42 which houses a solenoid ingot 43 and a reciprocating retainer 44. The solenoid control needle 45 is housed within the needle guide 46 which is disposed within the body of the injector 47 The needle seat 48 is interposed between the nozzle 45 and the atomizing nozzle 49, which directs the liquid / gas mixture into an air mixing nozzle 50. Between the atomizing nozzle 49 and the air mixing nozzle 50 a plurality of radially extending inspiratory passages 51 is disposed while around the ring 52 a plurality of tertiary inspiring passages 53 is disposed downstream of the outlet of the mixing nozzle 50 '. In the embodiment of FIG. 4 it has been found that in the order of 1% stoichiometric air at 100 psi coupled to an air inlet 54 has been sufficient to shear drops of fuel from a conical fuel blade, which fuel is supplied by means of the fuel inlet 55. • In order to better appreciate the operation of the air flow and needle movement, reference should be made to FIG. 5, which represents the circumferential opening 56 between the needle 45 and the hole within the body of the needle. injector 41 to allow the passage of high pressure gas after a conical liquid spray which is formed under the movement of the needle 45 from the seat 48. After the liquid has been sheared from the conical blade, it passes along of passage 56, through a plurality of circularly disposed passages 57 which are fed into an atomizing nozzle 49, then through the secondary air inspiration zone defined in FIG. FIG. 6 shows a nozzle and nozzle arrangement of FIG. 4 mounted on top of an inlet manifold venturi 60. A further arrangement of the inlet manifold 60 is provided by the passages 51 before being introduced into the air mixing nozzle 50. Referring to FIG. Potential installation is shown in Figure 7 wherein the embodiment of Figure 4 is mounted on an inlet manifold of naturally inspired or supercharged air 70 with a passage of air bladder 71 which feeds air to the inlet manifold to provide air secondary between nozzles 49 and 50. Figure 8 shows yet another mounting arrangement for an air intake manifold; supercharged 80 wherein the injector 41 is mounted on the manifold 80, with the manifold air being fed directly. within the passages 51 rather than by means of a step arrangement as in Figure 7. While the nozzles of the embodiments shown in FIG. In conjunction with the mixing apparatus, it will be appreciated that each nozzle can be used in a simple or multi-stage manner in any application where a liquid / gas mixture is to be supplied to any relevant design criteria. It will be appreciated by those; persons skilled in the art that numerous variations and / or modifications can be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention, as is amply described. The present modalities must therefore be considered in all