WO2012085901A2

WO2012085901A2 - Valve covered orifice pressure equalizing channel

Info

Publication number: WO2012085901A2
Application number: PCT/IB2012/051770
Authority: WO
Inventors: Vilis I. Lietuvietis
Original assignee: Lietuvietis Vilis I
Priority date: 2011-05-09
Filing date: 2012-04-11
Publication date: 2012-06-28
Also published as: WO2012085901A3

Abstract

The invention pertains to a direct injection injector employing an improved valve covered orifice nozzle valve. It provides a nozzle hole fuel pressure boosting and equalizing groove (2) in its tapered stopper part (5) which lifts from its closed position substantially preventing trapped fuel leakage to its nozzle valve orifices, to their axial level while needle lift is still relatively low, connecting them to a path of substantially reduced flow resistance via said groove (2) (improving orifice pressure), providing faster (sharper, more abrupt and energetic) onset of the injection pulse (with better penetration), faster cutoff of the injection pulse, reduced sensitivity to valve closure element radial eccentricity in its valve seat, improving the symmetry of the ejected fuel plumes pattern, and permitting (not requiring) significantly reduced valve lift (and wear) for comparable injection performance. These advantages offer more agile and precise fuel injector performance for internal combustion engines.

Description

Valve Covered Orifice Pressure Equalizing Channel FIELD OF THE INVENTION

The present invention relates to a direct injection fuel injector for an internal combustion engine, and particularly to a direct injection injector nozzle of the valve covered orifice type.

PRIOR ART

Japanese Patent JP2008038716

PROBLEM TO BE SOLVED: To provide a VCO (Valve Covered Orifice) type fuel injection valve which uniformly sprays fuel even when nozzle holes are formed in positions of different distances from a seat part.

SOLUTION: The fuel injection valve 1 is formed so that a needle valve 20 reciprocating in an axis NA direction is disposed in a nozzle body 10 formed with the plurality of nozzle holes 11 a, 11 d in a tip and closes the nozzle holes when the seat part 21 of the needle valve 20 is seated in the nozzle body. The plurality of nozzle holes include those disposed at the positions different in distance from the seat part. An inner wall 13B of the nozzle body is formed with elongate grooves 12a, 12d disposed symmetrically about the axis and the nozzle holes 11 a, 11 d are formed in the elongate grooves 12a, 12d.

Critique of JP2008038716: This patent proves that the problem addressed by the present invention has aroused the attention of practitioners of the art. Specifically, the cited invention recognizes that radially eccentric VCO needle position produces harmful assymetric spray pattern, which may be improved by providing fluid flow channels to act as collectors of fluid pressure when the VCO valve is in its open position, which relieves fuel pressure starvation to the affected nozzle holes. Although the cited invention bears a resemblance in approach to the present invention, it is nevertheless significantly different, and distinctly inferior in meeting a key objective of the present invention, which is to totally seal the injector nozzle against the possibility of fuel leakage when the nozzle valve is in the closed position. This latter important feature is violated in the cited patent, due to the location of the nozzle holes within axially oriented („ vertical") grooves in the surface of the valve seat cut into the stationary nozzle body body, and not the moving valve closure element, such that one such groove is allocated to each nozzle hole. Because of this arrangement, each nozzle hole continually exposes the pressure equalization vertical grooves to the heat and pressure variations of the combustion chamber, which will certainly boil out a substantial part of the fuel trapped in each such vertical groove when the valve is closed, besides creating a hazard of injecting combustion gases along with coking of the interior of the nozzle holes due to this kind of cavity breathing during the combustion phase. In contrast, the present invention applies its annular groove of the preferred embodiment to a shielded position below the nozzle holes, sealing the fuel contained within the groove during the combustion phase so that it can not escape.

WO2007024418A1.pdf on the other hand, which presents a VCO type injector valve design as does the present invention, applies an annular groove to the valve closure element similar to the present invention, but with fundamental and decisive differences, such that this groove is exposed to the combustion chamber both when the valve is closed as well as when the valve is open, but for an entirely different purpose than in the present invention. This cited invention suffers from exactly the same defect as the previous invention, in that the annular groove in the tapered stopper part of the valve closure element which mates with its valve seat, is continually exposed to the combustion chamber when the vlave closure element is in its closed position, likewise subject to weeping and boiling away, wasting fuel and causing pollution. When the valve closure element rises from its valve seat, this groove, which is shallow and broad to overlap the nozzle holes entirely, rises above the nozzle holes, which is completely backwards from the function of the present invention, in no manner fulfilling the objectives of the present invention.

Furthermore, this design is not intended to counteract the radial misalignment problem common to the tapered stopper parts of the valve closure elements of VCO fuel injectors, and does not suggest such a solution, insofar as is apparent to the present author.

US20030057299 represents a forerunner to the previous patent, as its prior art, and exhibits exactly the same problems, but in a far more striking visual manner.

EP0352926B2 presents an early version of a fairly typical VCO fuel injector, which is subject to all of the problems that the present invention is designed to overcome, foremost of which is the problem of radial eccentricity of the valve closure element, creating a nonsymmetrical radial fuel spray pattern, deleterious to the efficiency and emissions performance of the engine.

DISCLOSURE OF THE INVENTION

The object of the present invention is to provide a direct injection injector employing an improved valve covered orifice nozzle valve. It provides a fuel pressure equalizing axially moving groove, which may be a simple annular groove, which lifts from a position beyond exposure to its nozzle valve orifices to their same axial level while needle lift is still relatively low, connecting them to substantially reduced flow resistance via said groove (improving orifice pressure), providing faster (sharper, more abrupt and energetic) onset of the injection pulse (with increased injected fuel plume penetration into the combustion chamber), faster cutoff of the injection pulse, reduced sensitivity to valve closure element radial eccentricity in its valve seat, improving the symmetry of the ejected fuel plumes, and permitting (not requiring) significantly reduced valve lift (and wear) for comparable injection performance. Reduced valve wear enables reduction of the valve seating contact area requirement, enabling reducing the distance between the nozzle seating (sealing) boundary and the nozzle holes, with the result that fuel flow restriction may be reduced, resulting in increased pressure at the nozzle holes, reducing the need for higher fuel rail pressures. These advantages serve the goal of more agile and precise fuel injector performance neccessary to attain the more demanding and precise injection control to achieve improved internal combustion engine efficiency (improved fuel economy and power with reduced undesirable exhaust emissions) for all kinds of internal combustion engines (gasoline, diesel, gaseous fuel, two cycle, four cycle, six cycle, etc., using all kinds of injected fluid media).

The first example embodiment of the present invention as presented in the drawings presents the simplest, and possibly the most advantageous embodiment, whose primary purpose is to counteract the prevalent valve closure element radial excentricity of VCO injectors from spoiling the neccessarily radially symmetric injector spray pattern, but exhibits a major dividend unexpected bonus effect of creating substantially faster and highly beneficial and prized injection pulse rise and fall speeds, just described.

This performance is achieved by placing a fuel channeling fuel pressure equalizing groove a short distance (which may be infinitesimal) beneath the circular distribution of nozzle holes penetrating the valve seat and necessarily substantially or practically (adequately) sealed from the combustion chamber during the combustion process, which was the basic original purpose of the VCO design. „Beneath" means in the narrowing direction of the valve seat taper to the point where this groove is for practical purposes sealed from leaking its contents into the nozzle holes, yet still in sufficiently near proximity to these holes so that a small valve lift (in the example embodiment approximately 50μηι) will thoroughly expose all of the nozzle holes to the fuel collecting and channeling effect of this groove, (accomplishing an approsimately 2/3 lateral, or radial plane overlap of the groove and the nozzle holes. In the case of a drift off of the valve seat axis of the nozzle needle valve, fuel is redistributed to the obstructed, fuel starved nozzle holes, by the groove channeling fuel pressure and flow from the opposite side of the nozzle valve from the unobstructed holes to the obstructed holes. According to the present invention, only negligible fuel weepage, if any, would be possible according to the present invention and its example embodiments, fully meeting the original purpose of the VCO design approach. This is because the fuel channeling groove is substantially sealed from the combustion chamber when the nozzle valve is in its closed position.

An important effect of the fluid medium pressure equalizing groove is that it functions as a distributor of fuel pressure and flow which reduces the net nozzle valve restriction to fuel flow to the nozzle holes (the effect of which is to raise the fuel pressure at the nozzle holes) by providing shorter restricted (narrow) paths for fuel flow to a low pressure sink (discharge destination) than is available when only the nozzle orfices alone provide such a low pressure sink. Thus high pressure fuel injected into the opened gap between the valve seat and its conforming tapered stopper part is drawn, or attracted to the broad diameter annular ring of relatively low current sinking pressure at the immediate level and proximity of the nozzle holes, rather than by the fuel current sinking effect of the very narrow nozzle holes alone, which present a much smaller fuel discharge area, and at considerably greater diagonal distances to the nozzle holes from any given inlet point along the annular entry point of the tapered stopper part (see FIG 5).

As the nozzle hole pressure boosting and equalizing groove rises from a position below the lower edges of the inlet orifices of the nozzle holes, (where due to the VCO effect of the valve needle's tapered stopper part having sealed the nozzle holes sufficiently to prevent significant leakage from the trapped fuel volume downstream of the pressure tight valve seating upstream boundary located upstream from the inlet orifices of the nozzle holes), the fuel volume trapped within the nozzle hole pressure boosting and equalizing groove rises very early in the valve lift trajectory (namely by a relatively short axial distance) from a position hidden from the nozzle holes to within low resistance (unimpeded) fluid communication with the nozzle holes. At this point of early nozzle flow the equalizing groove begins to act in an uniform manner around its circumference as a fuel collector (experiencing a fuel pressure drop due to exposure to the nozzle holes) at a relatively low flow rate and relatively high pressure due to that low flow rate in combination with a relatively low pressure gradient spread over the large circumference of the pressure equalizing groove, and channels that fuel collected at a relatively low flow velocity and relatively high pressure due to exposure to the inflowing low velocity fuel around the groove to near proximity with the inlet orifices of the nozzle holes. Now what happens is that this relatively high pressure is presented immediately in front of the nozzle holes at a flow rate which is much higher than the uniformly distributed low inflow rate into the pressure equalizing groove 22, but at essentially the same pressure. This discharge flow rate from the pressure equalizing groove 22 is substantially higher than in the absence of said groove 22 due to the relatively large cross section of the pressure equalizing groove 22 offering low resistance to hydraulic flow within its channel (low pressure drop) in comparison with the relatively small area encircling the nozzle hole orifice in the absence of the annular groove. Whatever the cross sectional area of said groove, large or small, it augments, adds to, the available inflow cross section area surrounding each nozzle hole orifice. Therefore there exists an optimum depth and width, or cross section area, of such a pressure equalizing groove beyond which the nozzle hole fuel pressure is not substantially or at all increased, because the cross section area of the nozzle holes themselves ultimately limit this flow at any given fuel rail pressure. Therefore a groove located at a distance of a small fraction (may be infinitesimal) of the nozzle hole diameter below the nozzle hole, which has about the same width as the nozzle hole diameter, and a minimum depth of at least half of the nozzle hole diameter, may be adequate, and a groove depth and width of approximately the same or modestly larger than the diameter of the nozzle hole may possibly be near the optimum cross section of said groove for a VCO nozzle having a normal 5 to 7 nozzle holes, beyond which nozzle flow rate gains substantially diminish.

A benefit of such reduced net nozzle input flow resistance is a distinct increase in the response of the nozzles to eject their atomized fuel plumes for combustion, increasing both the fuel flow rise and fall times through the fuel injector, which increases the rate of energy production in the combustion proccess, and increases the precision of control available over the combustion process by application of more finely divided and distributed short injection pulses by computer control, making each of these shorter pulses more energetic in terms of combustion energy delivered to the combustion chamber, increasing the power output of the engine relative to the absence of the fuel pressure equalizing groove. This is true for both the normal nozzle valve lift of contemporary fuel injectors discussed in the following paragraph, or for the more interesting case wherein the nozzle valve lift is limited to about 50 or 60μηΊ.

The current state of the art uses nozzle hole diameters from 50μηη to 250μηι, with fuel pressures up to 2500 bar (Injector Nozzle Hole Parameters and their Influence on Real Dl Diesel Performance by MIKAEL LINDSTROM

http://kth .divaportal .org/smash/get/d iva2 : 159595/FULLTEXT01 ). See especially pages 38 -40, which suggest potential for satisfactory engine operation at low valve closure element lift, as low as 50μηι, when used in combination with the present invention as described below.

A transition to the use of smaller nozzle hole diameters than is currently common in the state of the art, namely from 100μηι to 250μηι, would serve not only the interests of finer atomization resulting in improved engine efficiency, but would enable the annular nozzle hole pressure boosting and equalizing groove to operate more effectively with a reduced groove cross section because less fuel flow capacity per unit length of the groove is needed to serve an increased number of nozzle holes of smaller diameter distributed throughout the length of the groove. This applies to the condition of a well-centered tapered stopper part of the valve closure element, which may not always be relied upon in various fuel injector designs. Fortunately, a 50μηι nozzle hole diameter along with 2500 bar pressures have been attained by the art.

According to the preceding reference, the reason for such eccentric operation is not well understood. However, the use of the fuel pressure equalizing groove, especially in combination with an increase of nozzle holes, which have a reduced diameter would certainly equalize the inflow of fuel around the valve seat, eliminating local differences between strong and weak flow. Such non-uniformity of flow may contribute to the tendency of the valve closure element to swing off center, which in the absence of the present invention would block some of the nozzle holes, and increase the exposure of their opposite nozzle holes to free flow of fuel, creating an irregular radial spray pattern from the nozzle, spoiling the combustion process and engine efficiency. Once such unbalanced flow is initiated, it is possible that a positive feedback effect would accelerate this harmful process, the flow imbalances with their pressure differences contributing to an increase of this process. Thus the present invention may abate this harmful effect.

Also, needle radial position instability may increase with needle lift as well as the suggested deleterious positive feedback process, because destabilizing flow is greater with increasing needle lift. Therefore limiting needle lift by either increased spring bias or mechanical stops to the valve closure element travel may also limit this unwelcome radial instability.

A BRIEF DESCRIPTION OF THE DRAWINGS

The invention is further described in detail via examples of embodiments by reference to the accompanying drawings, wherein: drawing FIG 1 schematically depicts the present invention embodied in a classic VCO fuel injector nozzle body structure depicted in accurate proportions conforming to the 7mm ISO standard for fuel injectors, wherein the broadest part of the accurately scaled nozzle body shown represents 7mm. The fuel injector nozzle valve is in its closed position. drawing FIG 2 schematically depicts the VCO fuel injector nozzle of FIG 1 in its open position, the white gap between the two thick black lines outlining the respective valve parts representing the valve lift; drawing FIG 3 is an enhanced enlargement of the tapered valve stopper and nozzle hole parts copied from FIG 1 and turned 90° so that the lower part of FIG 1 which points downwards in FIG 1 points left in FIG 3. drawing FIG 4 represents an enhanced enlargement of the valve of FIG 3 in its open position, corresponding to FIG 2. drawing FIG 5 schematically depicts a fairly correctly scaled axial end view of a combination of the valve seat having four nozzle hole orfices, and the tapered valve closure element which is in the OPEN position such that their two surfaces would exhibit the small gap shown in FIG 4. The arrows represent the direction of the conical sheet of fuel flow in the gap between these two surfaces, flow which ends up in the four nozzle hole orfices shown; drawing FIG 6 schematically depicts an inherently low valve lift nozzle valve mechanism capable of perhaps 50 to 80 microns of valve lift, which is benefited by the present invention; drawing FIG 7 is an augmented version of the example embodiment of drawing FIG 3 wherein fluid flow feedeing (or supply) axially extending valve seat grooves, termed feeder grooves, have been cut into the surface of the valve seat for the purpose of augmenting the rate of fluid flow to the pressure equalizing groove (equivalent to increasing fluid pressure within the pressure equalizing groove and in turn at the nozzle orfices under conditions of fluid flow) - wherein the nozzle valve is in the closed position; drawing FIG 8 represents the embodiment of drawing FIG 7 with the nozzle valve open; drawings FIG 9 and 10, analogous to drawings FIG 7 and 8 show an embodiment permitting shortening of the feeder grooves of drawings FIG 7 and 8 by adding a second annular flow collector groove separated from the first annular flow collector gvoove by interconnect grooves; drawings FIG 11 and 12, analogous to drawings FIG 9 and 10 eliminate both the multiple interconnect grooves between the annular flow collector grooves as well as the multiple feeder grooves by employing a single annular feeder groove and a single annular flow collector groove wherein both are extended in the axial dimension; drawing FIG 13 shows a two dimensional representation of the annular feeder groove, making clear how this feeder groove which has a truncated conical shape avoids cutting into the proximity of the nozzle hole apertures in the valve seat; drawing FIG 14 shows the analogue of drawing FIG 7 in the case where cutting channels, namely the feeder grooves, into the valve seat must be avoided, leaving the only option to cut analogous channels into its mating tapered stopper part (the valve sealing tip of the valve closure element). This drawing shows the nozzle valve in the closed position; drawing FIG 15 shows the valve of drawing FIG 14 in the open position, illustrating how the annular groove 2 in the tapered stopper part is raised into juxtaposition with the nozzle holes; drawing FIG 16 shows in a two dimensional schematic view how an annular feeder groove analogous to that of FIG 13 would appear in the case where cutting channels into the valve seat is to be avoided. In this case the dashed lines indicate the position of the nozzle hole apertures in the valve seat in the nozzle valve closed position; drawing FIG 17 shows a view like FIG 3 but having a larger diameter nozzle hole and nozzle hole pressure boosting and equalizing groove in its right hand half, with the view as in FIG 3 as its left hand half, wherein hydro-erosive grinding of the right hand nozzle hole inlet orifice corner is indicated by dashed lines. FIG 17A is an enlargement of this detail, with FIG 17B showing the actual hydroerosive ground surface instead of the dashed lines. The purpose of the drawing is to demonstrate visually the validity that the small gap, or channel of fluid communication between the nozzle hole pressure boosting and equalizing groove 2 and the nozzle hole 3 should not be likely to produce significant loss of fuel to the combustion chamber in the valve closed position, due to the capillary effect of the trapped fuel, an the vacuum effect also holding the trapped fuel, plus the cooling effect of the valve needle preventing vaporization of the fuel trapped within the nozzle hole pressure boosting and equalizing groove 2.

DETAILED DESCRIPTION OF EXAMPLES OF EMBODIMENTS

The present invention is further described from the description of examples of

embodiments of the invention by generally sequential reference to the accompanying cross-referenced and interrelated drawings, wherein the relative proportions and scale of any drawing is intended to be reasonably realistic.

In the ollowing descriptions of drawings of diverse embodiments, genrically identical details and element are designated with identical reference numbers.

Note that the example embodiments illustrated in the drawings exhibit an unusually small valve lift of approximately 50 or 60 microns according to the scale and resolution of the drawings. Such a small valve lift may be regarded as an illustrative convenience for those practitioners of the art wh realize that valve lifts of 200 microns have practically always been the norm for the over 20 years of existence of valve covered orfice (VCO) injector nozzles. On the other hand, valve lifts of 50 microns may be realizable in the future, particularly with the help of the present invention which enables increased flow of fuel at what were under the state of the art restrictively reduced valve lifts. Therefore, by aid of the present invention, and with the progress of the art, valve lifts of 50 or 60 microns may be realizable in the future.

Drawing FIG 1 illustrates by a sectional view a radially symmetric direct injection fuel injector nozzle body 1 embodied in a classic valve covered orfice (VCO) fuel injector nozzle body structure depicted in accurate proportions conforming to the common 7mm ISO standard for fuel injectors, wherein the broadest part of the accurately scaled nozzle body 1 shown represents 7mm. The fuel injector nozzle valve is in its closed position. The invention is represented by the horizontal line indicating the nozzle hole pressure boosting and equalizing groove 2 a short axial distance below the inlet apertures for the two nozzle holes 3 shown in the composite cross section and frontal aspect view, the enclosed valve closure element 4, in the present illustration being a valve pintle, or„needle", being shown in a frontal aspect view of its exterior surface. The VCO principle of operation is clearly seen in FIG 1 , wherein a valve closure element 4 generally conical valve sealing surface tightly contacts its identical conical seating surface on the inside of the nozzle body 1 , and in this seating surface terminate the inlet orfices of the nozzle holes 3, which are solidly and totally blocked shut by the closed valve, which is the characteristic principle of the VCO nozzle valve.

Drawing FIG 2 schematically depicts the VCO fuel injector nozzle of FIG 1 in its open position, representing fairly accurately an axial valve lift of 50 to 60μηι, the white gap between the two thick black lines outlining the respective valve parts representing said valve lift. Also, the two nozzle holes 3 shown as solid black lines fairly accurately in proportion represent holes of 50μηη diameter, wherein the thickness of the black lines accurately represent the relative diameter and length of these nozzle holes 3. Also clearly visible is the tapered stopper part 5 of the valve closure element 4, whose conical surface mates accurately with its identical conical surface in the valve seat 6, opening the visible white gap between the two to admit fuel pressure to reach the inlet orfices of the nozzle holes 3 to produce a fuel injection spray. It is this gap which becomes unsymmetric when the valve closure element 4 becomes radially displaced in some fuel injector designs more than in others, blocking the nozzle holes 3 on one side of the nozzle to produce an unacceptable non symmetric radial spray pattern from the holes. It is this common defect of the VCO design which inspired the present invention as a technical solution, which has been much written about and the subject of at least one recent Japanese invention cited in the prior art of the present document.

Drawing FIG 3 is an enhanced enlargement of the tapered nozzle valve stopper and nozzle hole parts directly copied from FIG 1 and turned 90° so that the lower part of FIG 1 which points downwards in FIG 1 points left in FIG 3. The enhancements show fine and important details invisible in FIG 1 due to their being lost due to the coarse thickness of the lines in the enlarged view of FIG 3. In specific, the 50μηι diameter nozzle holes 3 now clearly show their hole boundaries, including the inlet and outlet orfices. The nozzle hole pressure boosting and equalizing groove 2 is shown in a frontal aspect view, revealing the Bezier curve contour of the groove, and its clearly sealed position approximately 25μηη below (downstream of) the edges of the nozzle holes 3 when the nozzle valve is closed. The 25μηη figure appears appropriate for a long stem ISO standard nozzle body 1 outer diameter of 7mm, and would be scaled proportionately for other nozzle outer diameter sizes. The gap indicated at the tip of the tapered stopper part represents the amount of the valve lift 7 shown in FIG 4.

Drawing FIG 4 represents an enhanced enlargement of the nozzle valve of FIG 3 in its open position, corresponding to FIG 2. Here can be seen the valve lift of 50 to 60μηι at the tip of the tapered stopper part 5 between the closed tip position 8 and the open tip position 9 and the advantageous lifted working position of the nozzle hole pressure boosting and equalizing groove 2 relative to the nozzle holes 3 fed by this groove. Also seen clearly is the tapered stopper to valve seat gap 10 between the tapered stopper part 5 and the valve seat 6. Of interest is the efficient Bezier curve hollow surface contour and proportions, of approximately equal width and depth equal to about the nozzle hole diameter, of the nozzle hole pressure boosting and equalizing groove 2, as measured at and from the surface of the tapered stopper part 5, which is of unlimited nature within the bounds of the claims, and has potential for substantial inner enlargement to increase annular fuel flow within the groove without widening its surface aperture which in the present instance is about 50μηι, (equal to the nozzle hole 3 diameter) by making the channel of the groove deeper or broader by undercutting the surface, or both. The Bezier curve cross section contour of the nozzle hole pressure boosting and equalizing groove 2 reveals that its end points are substantially tangent to the perpendicular to the nozzle valve axis. This, for practically all inward opening nozzle valves is very beneficial in providing approximately a 120 degree surface angle (broad) at the nozzle hole edge, and approximately a 60 degree surface angle (narrow) at its opposite edge, farther from the nozzle holes 3, which reduces cavitation of fuel entering the nozzle holes at low valve lifts, and where the opposite 60 degree angled edge can not produce such cavitation due to the high valve lift when it approaches the edge of the nozzle hole 3. No rounding of either of these edges is neccessary nor desirable, because these edges are not susceptible to hydro erosion in service, as are the inlet orifice edges of the nozzle holes 3, for which reason hydro-erosion grinding is performed to remove these inlet orifice edges prior to service. In the present illustration the Bezier curve contoured groove is angled slightly upwards, at a good angle to direct its feeding flow toward the nozzle hole 3 inlet orfices adjacent to it, reducing both flow resistance and cavitation, possibly reducing the neccessity and/or the amount of hydro-erosion grinding required to attain the current level of nozzle flow and anti-erosion performance. Its specification is flexibly tailored to the individual application.

At this point, the independent claim 1 may be understood to embrace drawings FIG 3 and 4, as well as the following more complex drawings involving branches and extensions to the nozzle hole pressure boosting and equalizing groove 2 all of which extend upstream and above the axial level of the nozzle holes 3. The complexity of the wording of claim 1 , as well as some similar complexity in some of the dependent claims, addresses the broad variety of structures which these branches of said groove 2 may comprise. Yet the unifying principle, or underlying concept of the wording of claim 1 in this regard is very simple: For the fuel injector nozzle valve to overcome engine performance and emissions challenges, the inlet aperture of any nozzle hole 3 in the nozzle valve closed position must precisely limit its exposure to (overlap with) the nozzle hole pressure boosting and equalizing groove 2 or any of its branches, wherein such branches may include annular grooves as is illustrated in FIG 9, 10, 14, 15, and 16. In these drawings to come, branches bearing the reference numbers 12 and 14 are in fact groove branches of the tapered stopper part 5 branching off from the nozzle hole pressure boosting and equalizing groove 2, which may thus be regarded as branches of said groove 2, which are in fact practical illustrations of the potentially complex branched nozzle hole pressure boosting and equalizing groove 2 specification of claim 1 , despite the fact that these branches are designated with reference names and numbers other than that of said groove 2. It is obvious in these cases that in certain rotational positions these branches will overlap the inlet aperture of a nozzle hole 3, which must be avoided, and can be avoided by use of rotational limiting means applied to the tapered stopper part 5 (ie the valve needle).

Therefore, taking into consideration such a groove structure, claim 1 takes pains to express the essential conditions for the the nozzle hole pressure boosting and equalizing groove 2, and any possible branches that it may comprise, to avoid overlapping the inlet orifice of any nozzle hole 3 in the nozzle valve closed position by any groove of the tapered stopper part 5 except the single groove or groove segment of the nozzle hole fluid medium pressure boosting and equalizing groove 2 as found traversing the same azimuthal sector which bounds (ie exclusively limits) a nozzle hole (3) inlet orifice and which is immediately below or partly overlapping, axially, the nozzle hole 3 orifice. In other words, outside of this specified sector for any nozzle hole 3, the nozzle hole pressure boosting and equalizing groove 2 may extend axially or azimuthally without limit, so long as it fulfils the specified axial elevation limit of the claims within the azimuthal sector limits of the inlet aperture of a nozzle hole 3. Drawings FIG 14, 15, and 16 are particularly challenging to formulate into a comprehensive claim 1 , because in these figures, as can be seen clearly in FIG 16 , there are branches departing from the nozzle hole pressure boosting and equalizing groove 2 which pass through the bounding sector of a given nozzle hole 3 aperture which traverse that sector above, or upstream from, the nozzle hole 3 aperture so as to avoid it, while at the same time the limiting condition on the the nozzle hole pressure boosting and equalizing groove 2 is that its upper edge must remain below a limiting point (varying with various claims) of overlap limit with said nozzle hole 3 orifice. Therefore claim 1 specifies an upper axial limit of permitted overlap with said nozzle hole 3 orifice, while also permitting branches from or extensions of said groove 2 to traverse that same limiting sector at a higher axial level than said nozzle hole 3 orifice in the nozzl valve closed position, which does not overlap the nozzle hole 3 orifice.

Therefore, Claim 1 describes the invention as:

Claim 1. A direct injection injector (ie. a direct injector) for an internal combustion engine for spraying a fluid medium into the engine's combustion chamber of the valve covered orifice type, as viewed or depicted with its nozzle body 1 tip pointing "down" (ie "lower", as opposed to "higher"), wherein the injector comprises a nozzle body (1 ), which comprises at least a valve closure element, 4 which comprises a substantially tapered stopper part 5, which substantially conforms to its mating valve seat 6 in the nozzle body 1 , which when seated against its at least one pressure tight conforming surface or line of contact with valve seat 6, said tapered stopper part 5 seals against leakage to the combustion chamber from any fuel volume(s) trapped by said surface or line contact by covering an array of one or more nozzle hole 3 orifices, described in reference to the cylindrical coordinates of the nozzle valve axis, radius, and azimuth angle or sector, which is characterized in that the tapered stopper part 5 comprises in its valve sealing surface at least one nozzle hole fluid medium pressure boosting and equalizing groove 2 of indefinite, unlimited shape, size, or extent in terms of limitless possible interconnecting fluid communicating member branches or sections, in fluid communication with the fluid volume disposed in the tapered stopper to valve seat gap 10 between the surface(s) of the valve seat 6 and its mating surface(s) of the tapered stopper part 5 when said valve is in its open tip position 9; and wherein in the valve closure element 4 closed tip position 8, said groove 2 comprises an axially upper edge of azimuthal extent adjacent to its respectively opposite lower edge (admitting possible islands in a groove, or horizontal branching of said groove into parallel channels producing multiple upper and lower groove edges in a cross section profile of the tapered stopper part 5, whose axis lies in the cutting plane), such that: said groove 2 upper edge comprises an axially highest point of nearest approach to from below or greatest overlap with from below of a nozzle hole 3 inlet orifice, and is subject to the condition that groove 2 is found traversing the same azimuthal bounding sector (angular boundaries) of said nozzle hole 3 inlet orifice, and wherein other than that just described, no part of any tapered stopper part 5 groove or groove segment overlaps said nozzle hole 3 inlet orifice, and wherein said axially highest point of nearest approach is disposed no higher than (ie no further from the tip of nozzle body 1 than) the nozzle body 1 axial level of the point of intersection of the axis of the nozzle hole 3 with the nominal surface (ignoring any holes or grooves) of the valve seat 6; and which groove 2 when the valve closure element 4 moves to its open tip position 9, approaches axially to flow rate improving (ie viscous flow resistance reducing and hence fluid pressure increasing) fluid communication proximity of said nozzle hole 3 orifice; and due to the opening separation of the conforming tapering mating surfaces, namely of the tapered stopper to valve seat gap 10, whereby said groove 2 throughout its extent attracts (draws) fluid medium of higher pressure from the tapered stopper to valve seat gap 10 than in said groove 2, being in immediate fluid communication with the nozzle holes 3 of lower pressure, establishing a channeling fluid communication flowing from said groove 2 to said proximate nozzle hole 3 orifice, whereby flow resistance for supplying said nozzle hole 3 orifice is reduced in comparison to the absence of said groove 2, thereby improving the overall flow rate of the nozzle valve for a given axial valve lift 7.

Claims 5 and 10 are also well illustrated by FIG 4:

Claim 5. A direct injection injector according to claims 1 to 4 wherein said nozzle hole pressure boosting and equalizing groove 2 is an annular groove.

Claim 10. A direct injection injector according to any preceding claim wherein valve lift disposes said nozzle hole pressure boosting and equalizing groove 2 aperture in the surface of tapered stopper part 5 to an axial level shared by a nozzle hole 3 inlet orfice fed by said groove 2.

Drawing FIG 5 schematically depicts a fairly correctly scaled axial end view of a combination of the valve seat having four nozzle hole orfices, and the tapered valve closure element which is in the OPEN position such that their two surfaces would exhibit the small gap shown in FIG 4. The arrows represent the direction of the conical sheet of fuel flow in the gap between these two conical surfaces, flow which ends up in the four nozzle hole orfices shown. The lesson intended by this drawing is that fuel flows by the shortest direct path first of all to the nozzle hole pressure boosting and equalizing groove 2, which presents a low pressure sink for the high pressure sheet of fuel flow by virtue of its enlarged flow channel leading directly to all of the nozzle hole orfices. Actual flow of course would be a distortion of this idealized picture depending on the relative cross sectional area of the groove and of the number and size of the nozzle holes distributed presumably equally around the groove in its open working position. This groove may be greatly enlarged without widening the surface gap of the groove, illustrating the operative principle of the inventive nozzle hole pressure boosting and equalizing groove. Because the groove is intended to represent minimal resistance to fuel flow.

Drawing FIG 6 schematically depicts an inherently low valve lift nozzle valve mechanism of the present inventor capable of perhaps 50 to 80 microns of valve lift, which is benefited by the present invention. Details of precisely how the depicted mechanism works are not disclosed in this drawing.

Drawing FIG 7 is an augmented or enhanced version of the example embodiment of drawing FIG 3 for the purpose of increasing the flow rate of fuel from the nozzle holes 3, wherein fluid flow feedeing (or supply) axially extending valve seat grooves, termed feeder grooves 11 , have been cut into the surface of the valve seat so as to avoid cutting into the sealing valve seat surface in the near proximity of the nozzle hole inlet orfices for the purpose of augmenting the rate of fluid flow to the pressure equalizing groove (equivalent to increasing fluid pressure within the pressure equalizing groove and in turn at the nozzle orfices under conditions of fluid flow) - wherein the nozzle valve is shown in the closed position. The presence of the feeder grooves 11 without the presence of the auxiliary azimuthally disposed flow collector groove 12 will decrease the resistence to fluid flow from the inlet to the valve seat gap 10 to the fuel pressure equalizing groove 2 and

consequently the inlet apertures of the nozzle holes 3, with the result that fuel pressure at the inlet of the nozzle holes 3 is increased. Also, it is noted that said feeder grooves 11 may be broadened in the radial direction until they merge into one continuous annular groove in the valve seat 6, with the provision that such a groove should avoid cutting into the fluid sealing valve seat surface in the near proximity of the nozzle hole orfices. Such a radial broadening of the feeder grooves ultimately into one continuous annular groove has the effect of substantially increasing the fluid pressure at the pressure equalizing groove 2 and the nozzle holes 3 during fuel flow.

Nozzle holes 3 are represented by an unique dot-dash line pattern to indicate that these lines, while disposed, as are all of the nozzle valve elements of the present drawings, in radial symmetry about the nozzle valve axis, differ from the elements depicted with more conventional solid or dashed lines in that the dot-dash lines occupy a different cross- section cutting plane, and specifically that the nozzle holes 3 do not intersect (namely they avoid) the feeder grooves 11 , despite the fact that they appear to, in the attempt to depict them in a single two dimensional drawing. This same principle applies to nozzle holes 3 depicted by dot-dash lines in drawings FIG 9, 10, 11 , 12, 14, and 15.

To increase this effect even more, a flow collector groove 12 is provided cut into the surface of the tapered stopper part 5 such that the feeder grooves 11 have their inlet ends in near proximity to the collector grooves (within a distance of one nozzle hole diameter), intersecting their axial level as shown. The substantial advantage of such a fuel collector groove is its substantially larger diameter and substantially closer proximity to the inlet to the valve seat gap 10, enhancing fuel flow into this flow collector groove 12, which increased flow is subsequently channeled to the nozzle holes via the feeder grooves 11 and the pressure equalizing groove 2.

In the closed position of the nozzle valve, care is taken to seal fluid communication from all of the grooves from the nozzle holes 3.

Drawing FIG 8 shows the same embodiment as in FIG 7 with the nozzle valve in the open position.

Drawings FIG 9 and 10, analogous to drawings FIG 7 and 8 show an embodiment permitting shortening of the feeder grooves of drawings FIG 7 and 8 by adding a second annular flow collector groove separated from the first annular flow collector groove by interconnect grooves 13. The advantage of this embodiment example reduction of the amount of material to be cut from the valve seat 6, which may be difficult of access for machining.

Claims best illustrated by FIG 10 are 14 - 16:

Claim 14. A direct injector according to any preceding claim, wherein one or more nozzle hole pressure boosting and equalizing groove 2 flow feedeing (or supply) axially extending valve seat groove(s) 11 , termed feeder groove(s) 11 , opening into the surface of the valve seat 6 avoiding near proximity to the the nozzle holes 3 sufficient to insure normal fluid leakage sealing integrity of the nozzle hole orfices when the nozzle valve is closed, having axial extent upstream of the nozzle hole pressure boosting and equalizing groove 2 in the tapered stopper part 5 when the nozzle valve is in the open position, are disposed in the valve seat 6 such that when the nozzle valve is in the open position, said feeder groove(s) 11 are in fluid flow enhancement proximity (which may include sharing of the same axial level or overlap) to the nozzle hole pressure boosting and equalizing groove 2 in the tapered stopper part 5.

Claim 15. A direct injector according to claim 14 wherein at least one feeder groove 11 in the valve seat 6 lies entirely upstream (in the direction of increasing valve seat 6 taper radius) from the nozzle hole pressure boosting and equalizing groove 2 in the tapered stopper part 5 when the nozzle valve is in the closed position, whereby fluid communication between said at least one feeder groove 11 and nozzle hole pressure boosting and equalizing groove 2 becomes blocked (ie covered by the tapered stopper part 5 surface) when the nozzle valve is in the closed position.

Claim 16. A direct injector according to claims 14 or 15 wherein at least two feeder grooves 11 are in mutual fluid communication by means of an azimuthally extending fluid communication groove in the valve seat 6 surface when the nozzle valve is in both the closed and open positions.

Drawings FIG 11 and 12, analogous to drawings FIG 9 and 10 eliminate both the multiple interconnect grooves 13 between the annular flow collector grooves 12 as well as the multiple feeder grooves 11 by employing a single annular feeder groove 11 and a single annular flow collector groove 12 wherein both are extended in the axial direction; The advantages of this embodiment example are reduction of the amount of material to be cut from the valve seat 6, which may be difficult of access for machining, as well as increased cross sectional area for improved fuel flow. Nozzle holes 3 are represented by an unique dot-dash line pattern to indicate that these lines, while disposed, as are all of the nozzle valve elements of the present drawings, in radial symmetry about the nozzle valve axis, differ from the elements depicted with more conventional solid or dashed lines in that the dot-dash lines occupy a different cross- section cutting plane, and specifically that the nozzle holes 3 do not intersect (namely they avoid) the feeder grooves 11 , despite the fact that they appear to, in the attempt to depict them in a single two dimensional drawing. This same principle applies to nozzle holes 3 depicted by dot-dash lines in drawings FIG 9, 10, 11 , 12, 14, and 15.

Claims best illustrated by reference to all of FIG 9, 10, 11 , 12, and 13 are claims 17 - 20:

Claim 17. A direct injector according to claim 16, wherein all of the feeder grooves 11 are interconnected in fluid communication with one another by azimuthally extending interconnecting grooves in the valve seat 6 such that this collective groove structure becomes annular, which also may be an annular groove encircling the valve seat 6 resulting in a single annular feeder groove 11 , with the provision that said annular groove does not cut into the fluid sealing contact face of the valve seat 6 in the near proximity of the inlet apertures of the nozzle holes 3 sufficient to retain a fluid seal to limit fuel leakage when the nozzle valve is closed.

Claim 18. A direct injection injector according to any one of the preceding claims, wherein the nozzle hole pressure boosting and equalizing groove 2 in the valve seat 6 is augmented in its nozzle flow enhancement function by at least one azimuthally disposed flow collector groove 12 in the tapered stopper part 5, which may be (an) annular groove(s), and/or which may comprise branches or excursions having axial extent, which in the closed position of the nozzle valve is disposed in the valve sealing surface of the tapered stopper part 5 upstream from the nozzle hole(s) 3 aperture(s) in the valve seat 6 surface (disposed in the axial direction of increased valve seat taper radius in the radial plane from said nozzle hole(s) 3 apertures), wherein augmenting fluid communication flow between said flow collector groove(s) 12 and the nozzle hole pressure boosting and equalizing groove 2 which lie at substantially different axial levels is enhanced by at least one feeder groove 11 , which may be an annular groove encircling the axis of the nozzle valve, opening the surface of the valve seat 6 and having an axial component of extent such that when the tapered stopper part 5 is in its open position said nozzle hole pressure boosting and equalizing groove 2 and a flow collector groove 12 are each in fluid flow enhancing proximity with at least one and the same feeder groove 11 (by their

juxtaposition, or overlap, at a common or proximate axial level), and thereby also in fluid flow communication with each other. Claim 19. A direct injection injector according to claim 18, wherein at least two azimuthally disposed flow collector grooves 12 are annular grooves which in the closed position of the nozzle valve are in fluid communication with each other by means of interconnect grooves 13 in the surface of the stopper part 5 serving the function of transporting the fluid medium in the axial direction to the nozzle hole pressure boosting and equalizing groove 2.

Claim 20. A direct injection injector according to any of the preceding claims wherein at least one azimuthally disposed flow collector grooves 12 disposed in the tapered stopper part 5 is an annular groove comprising substantial axial component of extent (ie width) serving the function of transporting its fluid medium in the axial direction to the nozzle hole pressure boosting and equalizing groove 2.

Drawing FIG 13 shows a two dimensional representation of the annular feeder groove 11 , making clear how this feeder groove which has a truncated conical shape avoids cutting into the proximity of the nozzle hole apertures in the valve seat.

Note in FIG 7 - 12 that the nozzle holes 3 have been drawn with alternating dot and dash lines. This distinction is meant to represent the obvious fact that VCO nozzles must have their inner nozzle hole apertures covered (closed) when the valve is closed. However, due to the limitations of two-dimensional drawing, in order to accommodate depiction of the feeder grooves 11 , the feeder grooves 11 and the apertures, or entry points in the valve seat 6 of the nozzle holes 3 appear to overlap. Normally, for all relevant drawings, feeder grooves cut in the valve seat 6 are positioned half way between each pair of nozzle hole orfices cut in the valve seat 6. The feeder grooves 11 and the orfices of the nozzle holes 3 do not in fact overlap, because they exist in different radial planes containing the axis of the fuel injector nozzle as drawn. The plane of the drawing is one such radial plane comprising the axis of the nozzle, but in the case of FIG 7 - 12, the nozzle holes depicted by dot and dash lines exist in a different radial plane from that of these drawings, and therefore the nozzle holes 3 and the feeder grooves 11 do not in fact overlap, but merely exist at the same axial level of the drawing, which is neccessary for the proper function of the preferred embodiment examples shown.

Note that in drawings FIG 1 - 6 the valve closure element 4 is allowed to rotate freely with respect to the valve seat 6, but for all subsequent drawings, the nozzle hole 3 is depicted with a dot-dash line pattern, indicating that nozzle hole 3 must be rotationally limited to avoid coinciding (interfering) with the feeder groove(s) 11 , as indeed is seen where the dot- dash lines of nozzle holes 3 overlap the outlines of the feeder grooves 11 , which problem is explained by the fact that their cross sections occupy different radial cutting planes about the nozzle valve axis. Free valve needle rotation is the normal situation for practically all fuel injectors. However, there is nothing to prevent a designer from limiting this normally free rotation by introducing rotation limiting element(s) in the design. Indeed, claim 1 allows for either the presence or absence of such rotation limiting elements. The way in which clam 1 permits unlimited excursions and branchings of the fluid medium pressure equalizing groove would normally require a means for limiting the normally free rotation of the valve closure element in the case where in the nozzle valve closed position the claimed permitted unlimeted excursions and branchings of the fluid medium pressure equalizing groove extend to a level shared by the axial level of the nozzle hole apertures. In the absence of such a rotation limiting means there is a possibility that the valve closure element would rotationally drift into a position where the pressure equalizing groove overlaps one or more nozzle hole apertures, thus exposing the pressure equalizing groove to the combustion chamber when the fuel injector valve is in the closed position, causing fuel leakage and loss into the combustion chamber, which is just the situation that the valve covered orfice fuel injector definition is intended to prevent. In other words, in spite of the limitations of expressing 3-dimensional conical concepts in a 2-dimensional drawing, the underlying physical principle intended or implied in all of the drawings (for example by use of dot and dash lines in FIG 7, etc., to distinguish the nozzle holes as lying in a radial plane different from than that of the radial plane of the drawing which includes the line of the axis of symmetry of the nozzle valve) is that when the nozzle valve s in the closed position each of the nozzle hole apertures in the valve seat is covered and adequately sealed by a sufficient margin (surrounding border) of sealing contact depending on the pressure, of the mating and sealing surface of the tapered stopper part 5 of the valve closure element 4 (where in some instances such an nozzle hole 3 orfice sealing surface could be an island (or a peninsula) of the original surface of tapered stopper part 5 within stopper feeder groove 14 cut into the surface of tapered stopper part 5, whose maximum width would be determined by the rotational limits of the needle valve). Where danger of such a situation is present, as permitted but not required by claim 1 , the danger can be avoided by providing a means of rotational limitation for the valve closure element.

Drawing FIG 14 shows the analogue of drawing FIG 7 in the case where cutting channels, namely the feeder grooves 11 , into the valve seat 6 must be avoided, leaving the only option to cut analogous channels, termed stopper feeder grooves 14, into its mating tapered stopper part (the valve sealing tip of the valve closure element). This drawing shows the nozzle valve in the closed position. In this configuration, in order to prevent possible fuel leakage from the tapered stopper feeder grooves, which are in permanent fluid communication with the annular fluid medium pressure equalizing groove 2, and likewise with a possible flow collector groove 12, the free rotation of the valve closure element 4 must be limited to avoid radial (rotational) drifting of the feeder grooves 14 into fluid communication with the nozzle holes 3 when the nozzle valve is in the closed position. Such limiting means (eg. mechanical stops) is not illustrated, but may be implemented in a number of obvious ways clear to the practitioner of the art.

Drawing FIG 15 shows the valve of drawing FIG 14 in the open position, illustrating how the annular groove 2 (as assisted by its assisting stopper feeder grooves 14 and flow collector groove 12 in the tapered stopper part) is raised into juxtaposition with the nozzle holes;

Note that drawings FIG 14 and FIG 15 clearly suggest a simple example of application of the same identical principle to the embodiment of drawings FIG 11 and FIG 12, which is not illustrated for the reason of obviousness.

The claim best illustrated by FIG 14 -15 is claim 21 :

Claim 21. A direct injector according to any of the preceding claims wherein previously were established one or more feeder grooves 11 in the valve seat 6, such that instead of one or more of the feeder grooves 11 , wherein retention of any such feeder groove 11 is optional, its substantial mirror image is presently created (eg. transferred) into the surface of the tapered stopper part 5 as stopper feeder groove 14, being substantially its mirror image as established in the open position of the nozzle valve, which insures that stopper feeder groove 14 of the tapered stopper part 5 extends into fluid communication with nozzle hole pressure boosting and equalizing groove 2 as branch(es) of the latter, preferably accompanied by a means of rotational limitation of tapered stopper part 5 in order to prevent any part of any of stopper feeder groove(s) 14 from rotationally

(azimuthally) drifting into a position of fluid communication with any of the nozzle holes 3 when the nozzle valve is in the closed position.

Drawing FIG 16 shows in a two dimensional schematic view how an annular feeder groove analogous to that of FIG 13 would appear in the case where cutting channels into the valve seat 6 is to be avoided, by cutting analogous channel(s) into the tapered stopper part 5 instead. In this case the dashed lines indicate the position of the nozzle hole apertures in the valve seat in the nozzle valve closed position. Drawing FIG 16 illustrates claim 19. In this case, rotational stops for the valve closure element 4 are needed in order to maintain the position of the nozzle hole 3 orifice covering pads (or remaining islands of the surface of thetapered stopper part 5 which surface has elsewhere been removed - cut away to a deeper level in order to form the broad fluid channel termed stopper feeder groove 14 comprising said orifice covering pads or islands) which inhibit leakage of the fuel trapped in the stopper feeder groove 14, which in this case has been broadened to join its azimuthally adjacent stopper feeder grooves 14 to merge into a single annular stopper feeder groove 14, analogously to the corresponding discussion above regarding Drawing FIG 13.

The most likely application of the present invention would be to direct injection injectors according to ISO standards for 7mm and 9mm long-stem VCO multi-hole nozzles.

The claim best illustrated by FIG 16 is claim 22:

Claim 22. A direct injector according to claim 21 wherein in the closed position of the nozzle valve, a nozzle hole 3 aperture in valve seat 6 is covered by an island (also described as a "pad") of the original surface of the tapered stopper part 5 disposed within a part of the stopper feeder groove 14 as combined or merged with the nozzle hole pressure boosting and equalizing groove 2, which may be an annular stopper feeder groove 14 encircling the tapered stopper part 5, wherein the radial width of said island is conditioned by the rotational limits of valve closure element 4.

Drawing FIG 17 is a modification of drawing FIG 3, for illustration of the principles governing the positioning of the upper edge of the nozzle hole fuel pressure equalizing groove 2 in relationship with the lower edge of the nozzle hole 3. For purposes of positional and size reference, the left half of the drawing shows the nozzle hole 3 of FIG 2, having a bore diameter of 60 microns served by a nozzle hole pressure boosting and equalizing groove 2 also of 60 microns axial width, and the right half shows in

corresponding position a considerably more normal diameter nozzle hole of 110 microns diameter served by a nozzle hole pressure boosting and equalizing groove 2 of 150 microns axial width, featuring a Bezier curve contour wherein both ends of this curve are perpendicular to the nozzle body 1 axis, and the depth of the groove from the surface is equal to its width at the axial level of its minimum radial distance from the axis.

Due to the dominance in the state of the art of hydro-erosive grinding of fuel injector nozzle holes, for both smoothing the bore, but even more importantly, for rounding the inlet aperture corner, the present figure introduces an example of this popular technique as the hydro-erosive grinding orifice radius 15 of the nozzle hole 3 inlet aperture on the right hand side of the illustration. The positioning of the nozzle hole pressure boosting and equalizing groove 2 in reference to the hydro-erosive grinding orifice radius 15 must be considered carefully, as very small differences of its axial elevation in the valve closed position with respect to the nozzle hole 3 have the may result in large changes in engine performance, both desirable and undesirable.

Within a limited range, this elevation becomes an issue of engineering choice for the modification and optimization of the combustion characteristics, and for a correct understanding of this issue, the two addendum subsections below must be taken into consideration before proceeding with the present discussion.

In view of the two addendums below, it is clear that there is an implied and indefinite gap between the tapered stopper part 5 and the valve seat 6 in the nozzle valve closed position, normally practiced by the art which is not shown in any of the present document drawings, nor in FIG 17, (refer to FIG 4 which serves as a substitute for the valve open view of FIG 17 for the numbered item locations not shown in FIG 17), and there may be more than a single annular region or circle of seating contact between these two parts, all of which has been subject to a considerable variety of engineering variation, subject only to the limitations of the claims of the present invention.

The optimal axial elevation position of the upper edge of the nozzle hole pressure boosting and equalizing groove 2 is defined in relationship with the lower edgeof the hydro-erosion ground rounded inlet orifice of the nozzle hole 3. And this latter edge is obviously indistinct (and must be located by calculation and an agreed method for identifying this edge). For simplicity of argument in the present case, we shall define both the upper and the lower edges of the hydro-erosion ground nozzle hole 3 orifice as determined by the average (statistical) radius, wherein said edge is fixed, or established by the point where this calculated radius curve is found by calculation to be tangent to the nominal face of the tapered stopper part 5 in a cross section whose cutting plane comprises the axis of the nozzle body 1.

Furthermore, the technical usefulness of the present invention depends on unknown technical problems to which it may be applied, in the light of unknown experimental results yet to be determined, and therefore the defined upper limit axial position of the nozzle hole pressure boosting and equalizing groove 2 must be reasonably broad, and defined by a progressive succession of choices, or claims, each one more narrowly restrictive than its predecessor. It is clear according to the dissertation

"Injector Nozzle Hole Parameters and their Influence on Real Dl Diesel Performance" kth.diva-portal.org/smash/get/diva2:159595/FULLTEXT01 figure 25, pg. 39, that for a reasonably conventional modern passenger vehicle fuel injector as discussed, when the valve lift equals approximately the nozzle diameter, the nozzle holes limit the fuel flow, and the influence of the tapered stopper to valve seat gap 10 disappears entirely. The object of the present invention is to significantly increase the rate of fuel flow in the perfrmance region where the tapered stopper to valve seat gap 10 is absolutely limiting, as illustrated by the example of figure 25 on pg. 39 of the dissertation from zero valve lift to 0.05mm valve lift (50 microns valve lift), and obviously also for the following region between the region where the tapered stopper to valve seat gap 10 is absolutely limiting and where the total area of the nozzle holes 3 is absolutely limiting (namely, at a valve lift approximately equal to the nozzle hole diameter for a fuel injector aving 6 nozzle holes). Obviously, this scenario depends on the specific parameters of any given nozzle, but it does represent a typical, or majority case.

What should be avoided in this limiting of the axial position of the nozzle hole pressure boosting and equalizing groove 2 is excessive exposure of its trapped fuel volume to leakage through the nozzle holes 3. What is known is that an unspecified limited amount of such exposure is tolerable, preventing the vast majority of such potential leakage.

Therefore, in view of the cited figure 25, it seems reasonable to establish the upper limit for the position of the axial position of the nozzle hole pressure boosting and equalizing groove 2 at the axial level of the midpoint of the nozzle hole 3 aperture, or more

specifically, at the intersection of the axis of the nozzle hole with the nominal surface (ignoring any holes or grooves) of the valve seat 6, and its lower limit would be any point below the inlet orifice of a nozzle hole 3.

A more conservative upper axial limit for the upper edge of the nozzle hole pressure boosting and equalizing groove 2, and apparently a practical one, would be the lower edge of the nominal bore of the nozzle hole 3 before hydroerosive grinding is applied, or the lowest part of the intersection line of the virtual projection of the mathematical, or nominal bore surface with the nominal valve seat 6 surface.

The third and more conservative limiting level for the nozzle hole pressure boosting and equalizing groove 2 would be the lower edge of the nozzle hole 3 inlet orifice after it is rounded by hydro-erosive grinding, which is visually impossible to detect, but

mathematically may be found by the closest approximation to the rounded radius curve at the bottom of said orifice in the form of an arc of a circle having a radius which is the average radius of the physical curve. The tangent point of the nominal mathematical surface of the valve seat 6 to this circular arc (more precisely, we are describing a cross section view, whose cutting plane comprises the axis of the nozzle body 1 ) establishes the limiting axial elevation of the nozzle hole pressure boosting and equalizing groove 2. This is in effect, in different words, the same as in claim 1 of the present invention as claimed at the previous priority date.

Claims best illustrated by FIG 17 are 2 - 4, 6 - 9, and 11 - 13:

Claim 2. A direct injection injector according to claim 1 , wherein in the valve closure element 4 closed tip position 8, said nozzle hole pressure boosting and equalizing groove 2 has its axially highest point of its upper edge as described and limited in claim 1 with respect to and as found traversing the same azimuthal sector which bounds (ie exclusively limits) a nozzle hole 3 inlet orifice, disposed no higher than the nozzle body (1 ) axial level of the point of intersection between the nominal surface of the valve seat 6 (its

mathematical, or virtual ideal surface excluding holes, grooves, imperfections, or the like), and the tangent line to the nozzle hole 3 bore at the lowest level of said bore making tangential contact with said bore at a point measured along said tangent from said nominal surface of the valve seat 6 a distance equal to 1.3 times the average radius of said hydro- erosive grinding rounding of the lowest part of said inlet orifice edge.

Claim 3. A direct injection injector according to claim 1 , wherein in the valve closure element 4 closed tip position 8, in a cross section profile view, where the cutting plane comprises the nozzle body 1 axis, said nozzle hole pressure boosting and equalizing groove 2 has its axially highest point of its upper edge as described and limited in claim 1 with respect to and as found traversing the same azimuthal sector which bounds (ie exclusively limits) a nozzle hole 3 inlet orifice, disposed no higher than the lower boundary of the possibly, or optionally rounded corner (for example, rounded by hydro-erosive grinding) of a nozzle hole 3, and wherein in case of uncertainty, said lower edge may be specified by estimating its location by calculation of the average radius of said rounded corner comprising said rounded lower boundary, and replacing the cross section of the actual rounded edge (whose cutting plane comprises the nozzle body 1 axis) with the calculated segment of a circle of said average radius which is tangent to the nominal valve seat (6) surface, and wherein this point of tangency establishes said axially highest point of nozzle hole pressure boosting and equalizing groove 2.

Claim 4. A direct injector according to claim 1 , wherein in the valve closure element 4 closed tip position 8, said nozzle hole pressure boosting and equalizing groove 2 has its axially highest point of its upper edge as described and limited in claim 1 with respect to and as found traversing the same azimuthal sector which bounds (ie exclusively limits) a nozzle hole 3 inlet orifice, disposed in the range between and including the upper axial limits of respectively claim 2 and of claim 3 for the position of said upper edge, to within + or - 20% of the average nozzle hole radius, as calculated disregarding (excluding) any rounding of the nozzle hole 3 inlet orifice.

Claim 6. A direct injection injector according to claims 1 to 5 wherein said nozzle hole fluid medium pressure equalization groove 2 has an aperture width measured between the edges of said groove 2 at the tapered stopper part 5 surface equal to a range of 100% to 250% of the average nozzle hole 3 diameter, excluding any rounding of the inlet orifice,

Claim 7. A direct injection injector according to any preceding claim, wherein in the valve closure element 4 closed tip position 8, the corner line of intersection of the valve seat 6 surface with the nominal nozzle hole 3 surface (for example, straight cylindrical, outward tapering, inward tapering, convex bowed, concave bowed, etc), is rounded by hydro- erosive grinding or other means for the same purpose, eliminating said corner of nozzle hole 3, producing a rounded ("radiused") nozzle hole 3 inlet orifice, wherein the upper edge of the nozzle hole pressure boosting and equalizing groove 2, as described and limited in claim 1 as found traversing the same azimuthal sector which bounds (ie exclusively limits) a nozzle hole 3 inlet orifice, may share a same axial level as any point on the cross section contour (whose cutting plane comprises the nozzle valve axis) of the surface of said rounded part (as of a "rounded lip"), of the lowest part (ie toward the nozzle tip) of the orifice of the nozzle hole 3.

Claim 8. A direct injection injector according to any preceding claim, wherein both edges of the nozzle hole pressure boosting and equalizing groove 2, where they intersect the surface of the tapered stopper part 5 are substantially corner edges which corners result at the intersection of the smooth surface(s) of said nozzle hole pressure boosting and equalizing groove 2 and the smooth surface of the tapered stopper part 5, and wherein both tangents to the cross section profile (whose cutting plane comprises the nozzle valve axis) of the surface of the nozzle hole pressure boosting and equalizing groove 2 at both of these edges are substantially perpendicular to the axis of the nozzle body 1 to within plus or minus 15 degrees of angle.

Claim 9. A direct injection injector according to claim 8 wherein said cross section profile of nozzle hole pressure boosting and equalizing groove 2 is substantially a Bezier curve.

Claim 11. A direct injection injector according to any one of the preceding claims, wherein in the nozzle valve closed tip position 8, the tapered stopper part 5 surface aperture of the nozzle hole pressure boosting and equalizing groove 2, and specifically its upper edge as described and limited in claim 1 as found traversing the same azimuthal sector which bounds (ie exclusively limits) a nozzle hole 3 inlet orifice, is disposed beyond said nozzle hole 3 inlet orifice in the axial direction of reduced valve seat taper radius by a distance as measured from the nozzle hole 3 inlet orifice edge of less than the nozzle hole 3 inlet aperture radius.

Claim 12. A direct injector according to claims 5 through 11 wherein the depth of the nozzle hole pressure boosting and equalizing groove 2 is equal to at least half of its width as measured from and at the original (not grooved) surface of the tapered stopper part (5) of the valve closure element 4, wherein said width is measured edge to edge along the nominal tapered stopper part 5 surface, and said depth is measured perpendicular to said surface.

Claim 13. A direct injector according to claims 5 through 11 wherein the depth of the nozzle hole pressure boosting and equalizing groove (2) is substantially equal to or greater than its width as measured from and at the original (not grooved) surface of the tapered stopper part (5) of the valve closure element (4), wherein said width is measured edge to edge along the nominal tapered stopper part (5) surface, and said depth is measured perpendicular to said surface.

Addendum 1 for FIG 17: Regarding the absence of drawings or description of the location(s) of the line(s) of seating contact between tapered stopper part 5 and its mating valve seat 6. The location of the actual valve seat contact point in the present invention has not been specified, because this issue may be avoided (left as an engineering choice for the designer wishing to apply the present invention) for the present invention disclosure. All of the nozzle valve illustrations in the present document show the frustoconical tapered stopper part 5 having exactly the same cone angle as the

frustoconical valve seat 6, which is a conveniently descriptive approximating fiction in VCO nozzle illustration practice. It is common knowledge that frustoconical valve and valve seat geometries generally require application of slightly differing cone angles for the conical tip of the valve closure element and the valve seat, respectively. The result of such a cone angle difference is that the valve sealing contact occurs along a line of contact, which with normal valve wear broadens into a band of contact, and that the two mating surfaces diverge from each other in a linear manner with increasing distance downstream from the seating line of contact. Such a divergence generally establishes a small gap at axial level of the nozzle holes, such that the frustoconical needle surface does not tightly seal the nozzle hole inner orifices, suggesting a possibility of minor fuel leakage from the volume of said gap. However, practice has shown for VCO nozzles that this degree of gap between the needle and its seat does not result in significant loss of trapped fuel in the gap, in contrast with the loss from the sac of the sac type fuel injector. For this reason, the present document avoids entirely the issue of placement of the seating contact of the nozzle valve, leaving its choice(s) to the designer wishing to apply the present invention. Where the nozzle valve is illustrated with its cone is positioned with its pointed tip downward, as is normal, the classic arrangement for the VCO nozzle positions the line of contact at the top of the valve seat 6 and its congruent tapered stopper part 5 of the valve closure element 4, such that with wear of the seat, the contact broadens into a band with its lower edge migrating downward. Whereas multiple annular seating lines are often considered, a second, or an alternative single annular line of contact would be a few tens of microns above the row of nozzle holes.

One advantageous seating geometry for the present invention, used at least by the Bosch company, is named by the German acronym ZHI = Cylindrical Section (Z) with Groove (H), and Inverted (I) seat angle difference, wherein seating contact is made at a groove in the tapered stopper part 5 where the seating gap widens in the opposite axial directions (aboe and below) from the groove.

Note that the machining into the surface of the valve seat 6 as is apparent in FIG 7 - 10 may be accomplished by laser machining by positioning a small laser mirror at the end of a rod, possibly a hollow rod through which the laser beam is to pass, such that the mirror reflects the laser beam onto the inside surface which is to be machined.

Addendum 2 for FIG 17: Regarding the absence of drawings or description of k- factor nozzle hole geometry or its impact upon the understanding of the present invention. So-called "k-factor geometry", dominant in the present state of the fuel injector art, has not been touched upon in the present document, and its effect upon the present invention, while appearing to be a neutral issue to the author, may possibly raise questions or objections in details of the claims and specifications terminology. The issue is in how to deal in especially the specifications of the claims with the broadening of the diameter of the nozzle hole 3 inlet orifices due to the rounding of their initially sharp circular hole edge by hydro-erosive grinding. And specifically, how such orifice broadening might impact the preamble to claim 1 of the present invention describing the prior art of specifically VCO nozzles as originally written and claimed in its earliest priority date version:

... a substantially tapered stopper part (5), which substantially conforms to its mating valve seat (6) in the nozzle body (1 ), which when seated against its at least one pressure tight conforming surface or line of contact with valve seat (6), said tapered stopper part (5) seals against leakage to the combustion chamber from any fuel volume(s) trapped by said surface or line contact by covering an array of one or more nozzle hole (3) orifices, ... cha which is characterized in that

... wherein in the valve closure element (4) closed tip position (8), said groove (2) has its nearest point with respect to said nozzle hole (3) orifice disposed beyond exposure to (fluid communication with) said nozzle hole (3) orifice in the axial direction of reduced valve seat taper radius in the radial plane (ie„below the nozzle orfice" in the downstream direction of fluid flow), ...

Some might here, in view of the k-factor geometry rounding of the nozzle hole 3 orifice, and specifically its mention of "fluid communication", assume that there is absolutely no fluid communication between the nozzle hole 3 and said groove 2, such that a microscopic fish could not swim from one to the other. However, the practically universal practice of the art which provides a cone angle difference between the tapered stopper part 5 and its conforming valve seat 6 insures that in typical VCO nozzles a small tapering gap between these parts is present, without significantly, if at all, compromising the effective sealing of the valve covered orifice (VCO) in preventing fuel leakage through the nozzle holes 3 from the trapped fuel volume trapped below the circular line of contact, or annular band of surface contact, as in a worn fuel injector nozzle valve. It is significant that in the exceprt from the original claim 1 , above, we find in the preamble, or prior art part, clear reference to the "at least one pressure tight conforming surface or line of contact with valve seat (6)", which is universally understood to seal against fluid communication with the nozzle holes 3, and through them, communication with the combustion chamber. Thus, by this reference to the nozzle valve in its closed position is an unavoidable allusion to the practice of slightly differing cone angles for the taperd stopper part 5 and the valve seat 6, and by implication, the relative immunity in the experience of the practice of this art to leakage or seepage through the unavoidable gap at the axial level of the nozzle hole 3 inlet apertures of the contents of the thereby exposed trapped fluid volume in fluid communication with said gap, including the presence of rounding of the sharp original edges of the nozzle hole 3 inlet orifices, a presently dominant practice of this VCO art. Therefore it is the premise of the present invention that the upper edge (furthest from the nozzle tip) of the nozzle hole pressure boosting and equalizing groove 2 may share the same axial levels as the lower edge (nearest the nozzle tip) normal hydro-erosive ground rounded aperture edges of the nozzle holes 3 without violating the original claim 1 of the present invention, particularly as cited above.

The particular reasons why the VCO design is effective (it works) in sealing this trapped volume despite the fact that this seal is not perfect, indeed presenting a small and deliberate gap which is aggravated by hydro-erosion rounding of the sharp edge of the inlet orifice of the nozzle hole 3 are first, that its relatively incompressible fuel volume is trapped. Even water in a large pipe closed at one end will not immediately or quickly run out when quickly inverted due to low pressure ("vacuum") created at the closed end. But in the case of the small fluid spaces within a fuel injector nozzle, capillary action of the fuel within these restricted fluid spaces will further prevent, in addition to the force of vacuum created when an incompressible fluid is forcibly displaced from its trapped volume, the small volume from going anywhere, even subject to engine vibrations and combustion chamber pressure changes. What does affect a fluid in a trapped volume is heat in combination with being surrounded by a ring of holes exposed to the turbulent gas flow pressure fluctuations of the combustion chamber, severely challenging the opposing force of capillary action, as found in the sac of a sac type fuel injector nozzle located at the furthest extremity of the nozzle tip projecting into the heat of the combustion chamber, and isolated from the valve needle which is continually and throughout its considerable mass and length continually cooled by a fresh flow of fuel.

The cooling effect upon the trapped fuel in the tip of the VCO nozzle of this fuel cooled needle which forms half of the gap in the VCO nozzle is largely responsible for preventing leakage of the fuel, despite the fact that technically, and as conventionally understood by the practitioner of the art, there is always a small gap of fluid communication to the nozzle hole 3 in practically every VCO nozzle one might encounter. This has held true despite the advent of hydro-erosive grinding of the VCO nozzle holes 3, bringing the rounding and enlargement of their inlet orifices.

Therefore, the specification of the independent claim 1 of this invention can, and simply does ignore the presence of the physical enlargement of the nozzle holes 3 in their rounding by hydro-erosive grinding, or whatever other technique for a similar purpose or effect. Thus, even if the indeed sharp upper edge of the nozzle hole pressure boosting and equalizing groove 2 shared the same axial plane as any part of the rounded edge of the nozzle hole 3, creating an increase of the gap between them, this is an acceptable condition under the present invention.

And therefore, without prejudice against the correctness of the original wording of the claim 1 in its earliest priority date version, the present claim 1 is amended for clarity, and not in changing the original intent of the wording of claim 1 as quoted above, that the "perfect" sealing of the nozzle holes 3 by conventional VCO valve closure action is perfect in performance effect, though not in geometrical fact, to the satisfaction of the practitioner of the art, due to the preceding explanations.

More specifically, restriction, or limitation of the nozzle hole pressure boosting and equalizing groove 2 from being directly confronted by, or exposed in a direct line to the entire length of the entire bore of the nozzle holes 3, is the originally intended meaning of the quoted parts of the original claim 1 above. This condition excludes a direct line view from within the edge of the nozzle hole pressure boosting and equalizing groove 2 of a full circle of view into the combustion chamber through the nozzle hole 3. This specific condition is technically equivalent to the fictional situation of the nozzle holes having sharp and not rounded edges in hermetically sealing mechanical contact with the tapered stopper part 5 , which rounded edges are herein ignored, and as if the upper edge of the nozzle hole pressure boosting and equalizing groove 2 were in hermetically sealing contact with the valve seat 6, none of which is in fact true. But this untruth in the practice of the present invention does not have an adverse technical effect as explained above. And the present invention does not depend upon this fictional scenario.

The invention is not limited to the preceding descriptions and illustrations of example embodiments, but embraces numerous other embodiment possibilities within the limits of the claims.

Claims

1. A direct injection injector (ie. a direct injector) for an internal combustion engine for spraying a fluid medium into the engine's combustion chamber of the valve covered orifice type, as viewed or depicted with its nozzle body (1 ) tip pointing "down" (ie "lower", as opposed to "higher"), wherein the injector comprises a nozzle body (1 ), which comprises at least a valve closure element, (4) which comprises a substantially tapered stopper part (5), which substantially conforms to its mating valve seat (6) in the nozzle body (1 ), which when seated against its at least one pressure tight conforming surface or line of contact with valve seat (6), said tapered stopper part (5) seals against leakage to the combustion chamber from any fuel volume(s) trapped by said surface or line contact by covering an array of one or more nozzle hole (3) orifices, described in reference to the cylindrical coordinates of the nozzle valve axis, radius, and azimuth angle or sector, which is characterized in that the tapered stopper part (5) comprises in its valve sealing surface at least one nozzle hole fluid medium pressure boosting and equalizing groove (2) of indefinite, unlimited shape, size, or extent in terms of limitless possible interconnecting fluid communicating member branches or sections, in fluid communication with the fluid volume disposed in the tapered stopper to valve seat gap (10) between the surface(s) of the valve seat (6) and its mating surface(s) of the tapered stopper part (5) when said valve is in its open tip position (9); and wherein in the valve closure element (4) closed tip position (8), said groove (2) comprises an axially upper edge of azimuthal extent adjacent to its respectively opposite lower edge (admitting possible islands in a groove, or horizontal branching of said groove into parallel channels producing multiple upper and lower groove edges in a cross section profile of the tapered stopper part (5), whose axis lies in the cutting plane), such that: said groove (2) upper edge comprises an axially highest point of nearest approach to from below or greatest overlap with from below of a nozzle hole (3) inlet orifice, subject to the condition that groove (2) is found traversing the same azimuthal bounding sector (angular boundaries) of said nozzle hole (3) inlet orifice, and wherein other than that just described, no part of any tapered stopper part (5) groove or groove segment overlaps said nozzle hole (3) inlet orifice, and wherein said axially highest point of nearest approach is disposed no higher than (ie no further from the tip of nozzle body (1 ) than) the nozzle body (1 ) axial level of the point of intersection of the axis of the nozzle hole (3) with the nominal surface (ignoring any holes or grooves) of the valve seat (6); and which groove (2) when the valve closure element (4) moves to its open tip position (9), approaches axially to flow rate improving (ie viscous flow resistance reducing and hence fluid pressure increasing) fluid communication proximity of said nozzle hole (3) orifice; and due to the opening separation of the conforming tapering mating surfaces, namely of the tapered stopper to valve seat gap (10), whereby said groove (2) throughout its extent attracts (draws) fluid medium of higher pressure from the tapered stopper to valve seat gap (10) than in said groove (2), being in immediate fluid communication with the nozzle holes (3) of lower pressure, establishing a channeling fluid communication flowing from said groove (2) to said proximate nozzle hole (3) orifice, whereby flow resistance for supplying said nozzle hole (3) orifice is reduced in comparison to the absence of said groove (2), thereby improving the overall flow rate of the nozzle valve for a given axial valve lift (7).

2. A direct injection injector according to claim 1 , wherein in the valve closure element (4) closed tip position (8), said nozzle hole pressure boosting and equalizing groove (2) has its axially highest point of its upper edge as described and limited in claim 1 with respect to and as found traversing the same azimuthal sector which bounds (ie exclusively limits) a nozzle hole (3) inlet orifice, disposed no higher than the nozzle body (1 ) axial level of the point of intersection between the nominal surface of the valve seat (6) (its mathematical, or virtual ideal surface excluding holes, grooves, imperfections, or the like), and the tangent line to the nozzle hole (3) bore at the lowest level of said bore making tangential contact with said bore at a point measured along said tangent from said nominal surface of the valve seat (6) a distance equal to 1 .3 times the average radius of said hydro-erosive grinding rounding of the lowest part of said inlet orifice edge.

3. A direct injection injector according to claim 1 , wherein in the valve closure element (4) closed tip position (8), in a cross section profile view, where the cutting plane comprises the nozzle body (1 ) axis, said nozzle hole pressure boosting and equalizing groove (2) has its axially highest point of its upper edge as described and limited in claim 1 with respect to and as found traversing the same azimuthal sector which bounds (ie exclusively limits) a nozzle hole (3) inlet orifice, disposed no higher than the lower boundary of the possibly, or optionally rounded corner (for example, rounded by hydro-erosive grinding) of a nozzle hole (3), and wherein in case of uncertainty, said lower edge may be specified by estimating its location by calculation of the average radius of said rounded corner comprising said rounded lower boundary, and replacing the cross section of the actual rounded edge (whose cutting plane comprises the nozzle body (1 ) axis) with the calculated segment of a circle of said average radius which is tangent to the nominal valve seat (6) surface, and wherein this point of tangency establishes said axially highest point of nozzle hole pressure boosting and equalizing groove (2).

4. A direct injector according to claim 1 , wherein in the valve closure element (4) closed tip position (8), said nozzle hole pressure boosting and equalizing groove (2) has its axially highest point of its upper edge as described and limited in claim 1 with respect to and as found traversing the same azimuthal sector which bounds (ie exclusively limits) a nozzle hole (3) inlet orifice, disposed in the range between and including the upper axial limits of respectively claim 2 and of claim 3 for the position of said upper edge, to within + or - 20% of the average nozzle hole radius, as calculated disregarding (excluding) any rounding of the nozzle hole (3) inlet orifice.

5. A direct injection injector according to claims 1 to 4 wherein said nozzle hole pressure boosting and equalizing groove (2) is an annular groove.

6. A direct injection injector according to claims 1 to 5 wherein said nozzle hole fluid medium pressure equalization groove (2) has an aperture width measured between the edges of said groove (2) at the tapered stopper part (5) surface equal to a range of 100% to 250% of the average nozzle hole (3) diameter, excluding any rounding of the inlet orifice.

7. A direct injection injector according to any preceding claim, wherein in the valve closure element (4) closed tip position (8), the corner line of intersection of the valve seat (6) surface with the nominal nozzle hole (3) surface (for example, straight cylindrical, outward tapering, inward tapering, convex bowed, concave bowed, etc), is rounded by hydro- erosive grinding or other means for the same purpose, eliminating said corner of nozzle hole (3), producing a rounded ("radiused") nozzle hole (3) inlet orifice, wherein the upper edge of the nozzle hole pressure boosting and equalizing groove (2), as described and limited in claim 1 as found traversing the same azimuthal sector which bounds (ie exclusively limits) a nozzle hole (3) inlet orifice, may share a same axial level as any point on the cross section contour (whose cutting plane comprises the nozzle valve axis) of the surface of said rounded part (as of a "rounded lip"), of the lowest part (ie toward the nozzle tip) of the orifice of the nozzle hole (3).

8. A direct injection injector according to any preceding claim, wherein both edges of the nozzle hole pressure boosting and equalizing groove (2), where they intersec the surface of the tapered stopper part (5) are substantially corner edges which corners result at the intersection of the smooth surface(s) of said nozzle hole pressure boosting and equalizing groove (2) and the smooth surface of the tapered stopper part (5), and wherein both tangents to the cross section profile (whose cutting plane comprises the nozzle valve axis) of the surface of the nozzle hole pressure boosting and equalizing groove (2) at both of these edges are substantially perpendicular to the axis of the nozzle body (1 ) to within plus or minus 15 degrees of angle.

9. A direct injection injector according to claim 8 wherein said cross section profile of nozzle hole pressure boosting and equalizing groove (2) is substantially a Bezier curve.

10. A direct injection injector according to any preceding claim wherein valve lift disposes said nozzle hole pressure boosting and equalizing groove (2) aperture in the surface of tapered stopper part (5) to an axial level shared by a nozzle hole (3) inlet orfice fed by said groove (2).

11. A direct injection injector according to any one of the preceding claims, wherein in the nozzle valve closed tip position (8), the tapered stopper part (5) surface aperture of the nozzle hole pressure boosting and equalizing groove (2), and specifically its upper edge as described and limited in claim 1 as found traversing the same azimuthal sector which bounds (ie exclusively limits) a nozzle hole (3) inlet orifice, is disposed beyond said nozzle hole (3) inlet orifice in the axial direction of reduced valve seat taper radius by a distance as measured from the nozzle hole (3) inlet orifice edge of less than the nozzle hole (3) inlet aperture radius.

12. A direct injector according to claims 5 through 11 wherein the depth of the nozzle hole pressure boosting and equalizing groove (2) is equal to at least half of its width as measured from and at the original (not grooved) surface of the tapered stopper part (5) of the valve closure element (4), wherein said width is measured edge to edge along the nominal tapered stopper part (5) surface, and said depth is measured perpendicular to said surface.

13. A direct injector according to claims 5 through 11 wherein the depth of the nozzle hole pressure boosting and equalizing groove (2) is substantially equal to or greater than its width as measured from and at the original (not grooved) surface of the tapered stopper part (5) of the valve closure element (4), wherein said width is measured edge to edge along the nominal tapered stopper part (5) surface, and said depth is measured

perpendicular to said surface.

14. A direct injector according to any preceding claim, wherein one or more nozzle hole pressure boosting and equalizing groove (2) flow feedeing (or supply) axially extending valve seat groove(s) (11 ), termed feeder groove(s) (11 ), opening into the surface of the valve seat (6) avoiding near proximity to the the nozzle holes (3) sufficient to insure normal fluid leakage sealing integrity of the nozzle hole orfices when the nozzle valve is closed, having axial extent upstream of the nozzle hole pressure boosting and equalizing groove (2) in the tapered stopper part (5) when the nozzle valve is in the open position, are disposed in the valve seat (6) such that when the nozzle valve is in the open position, said feeder groove(s) (11 ) are in fluid flow enhancement proximity (which may include sharing of the same axial level or overlap) to the nozzle hole pressure boosting and equalizing groove (2) in the tapered stopper part (5).

15. A direct injector according to claim 14 wherein at least one feeder groove (11 ) in the valve seat (6) lies entirely upstream (in the direction of increasing valve seat (6) taper radius) from the nozzle hole pressure boosting and equalizing groove (2) in the tapered stopper part (5) when the nozzle valve is in the closed position, whereby fluid

communication between said at least one feeder groove (11 ) and nozzle hole pressure boosting and equalizing groove (2) becomes blocked (ie covered by the tapered stopper part 5 surface) when the nozzle valve is in the closed position.

16. A direct injector according to claims 14 or 15 wherein at least two feeder grooves (11 ) are in mutual fluid communication by means of an azimuthally extending fluid

communication groove in the valve seat (6) surface when the nozzle valve is in both the closed and open positions.

17. A direct injector according to claim 16, wherein all of the feeder grooves (11 ) are interconnected in fluid communication with one another by azimuthally extending interconnecting grooves in the valve seat (6) such that this collective groove structure becomes annular, which also may be an annular groove encircling the valve seat (6) resulting in a single annular feeder groove (11 ), with the provision that said annular groove does not cut into the fluid sealing contact face of the valve seat (6) in the near proximity of the inlet apertures of the nozzle holes (3) sufficient to retain a fluid seal to limit fuel leakage when the nozzle valve is closed.

18. A direct injection injector according to any one of the preceding claims, wherein the nozzle hole pressure boosting and equalizing groove (2) in the valve seat (6) is augmented in its nozzle flow enhancement function by at least one azimuthally disposed flow collector groove (12) in the tapered stopper part (5), which may be (an) annular groove(s), and/or which may comprise branches or excursions having axial extent, which in the closed position of the nozzle valve is disposed in the valve sealing surface of the tapered stopper part (5) upstream from the nozzle hole(s) (3) aperture(s) in the valve seat (6) surface (disposed in the axial direction of increased valve seat taper radius in the radial plane from said nozzle hole(s) (3) apertures), wherein augmenting fluid communication flow between said flow collector groove(s) (12) and the nozzle hole pressure boosting and equalizing groove (2) which lie at substantially different axial levels is enhanced by at least one feeder groove (11 ), which may be an annular groove encircling the axis of the nozzle valve, opening the surface of the valve seat (6) and having an axial component of extent such that when the tapered stopper part (5) is in its open position said nozzle hole pressure boosting and equalizing groove (2) and a flow collector groove (12) are each in fluid flow enhancing proximity with at least one and the same feeder groove (11 ) (by their juxtaposition, or overlap, at a common or proximate axial level), and thereby also in fluid flow communication with each other.

19. A direct injection injector according to claim 18, wherein at least two azimuthally disposed flow collector grooves (12) are annular grooves which in the closed position of the nozzle valve are in fluid communication with each other by means of interconnect grooves (13) in the surface of the stopper part (5) serving the function of transporting the fluid medium in the axial direction to the nozzle hole pressure boosting and equalizing groove (2).

20. A direct injection injector according to any of the preceding claims wherein at least one azimuthally disposed flow collector grooves (12) disposed in the tapered stopper part (5) is an annular groove comprising substantial axial component of extent (ie width) serving the function of transporting its fluid medium in the axial direction to the nozzle hole pressure boosting and equalizing groove (2).

21. A direct injector according to any of the preceding claims wherein previously were established one or more feeder grooves (11 ) in the valve seat (6), such that instead of one or more of the feeder grooves (11 ), wherein retention of any such feeder groove (11 ) is optional, its substantial mirror image is presently created (eg. transferred) into the surface of the tapered stopper part (5) as stopper feeder groove (14), being substantially its mirror image as established in the open position of the nozzle valve, which insures that stopper feeder groove (14) of the tapered stopper part (5) extends into fluid communication with nozzle hole pressure boosting and equalizing groove (2) as branch(es) of the latter, preferably accompanied by a means of rotational limitation of tapered stopper part (5) in order to prevent any part of any of stopper feeder groove(s) (14) from rotationally

(azimuthally) drifting into a position of fluid communication with any of the nozzle holes (3) when the nozzle valve is in the closed position.

22. A direct injector according to claim 21 wherein in the closed position of the nozzle valve, a nozzle hole (3) aperture in valve seat (6) is covered by an island (also described as a "pad") of the original surface of the tapered stopper part (5) disposed within a part of the stopper feeder groove (14) as combined or merged with the nozzle hole pressure boosting and equalizing groove (2), which may be an annular stopper feeder groove (14) encircling the tapered stopper part (5), wherein the radial width of said island is conditioned by the rotational limits of valve closure element (4).