Fluid injection nozzle

Abstract: According to the present invention, an injection nozzle portion of the fuel injection valve is set to have a relation of 2 < DS/DH < 4 , h < 1.5d, H < 3d, where DH is a pitch between orifices at the inlet surface (52a) of the orifice plate (52) in respect to an orifice diameter d of the orifice plate (52) in a fluid injection nozzle, DS is a seat diameter, H is a distance between the valve seat (251) and the orifice plate inlet surface (52a), h is a vertical line distance ranging from a needle flat surface to the orifice plate inlet surface (52a) when the abutting portion (263) of the needle (25) is moved away from the valve seat (251). In this way, a flow directed uniformly toward the orifice (52) is induced in a flat flow passage between the needle flat surface (82) and the orifice plate inlet surface (52a), and the fuel flows collide with each other just above the orifice inlet and then the fuel is injected from the orifice (52). Accordingly, the internal energy of the fuel can be effectively taken out in a form of disturbance of collision, the fuel can be effectively changed into fine particles, and at the same time the fuel atomization having a superior directional characteristic can be obtained.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention: The present invention relates to the fluid injection nozzle, and for example, an injection nozzle of a fuel injection valve for injecting and supplying fuel into an internal combustion engine for an automobile. 2. Description of Related Art: In such a prior art fuel injection valve as described above, "an atomization of fuel (fine fuel particle)" to be injected from an injection hole is one of the important elements in view of reduction of fuel consumption amount, improvement of exhaust emission, and a stable operating characteristic of the internal combustion engine and the like. As a method for facilitating the atomization of injected fuel, auxiliary atomizing means such as air collision against the injected fuel and heating around the injection hole or the like can be provided, although there is a problem in that these atomizing means are expensive. On the other hand, various kinds of methods for facilitating the atomization are proposed by providing the orifice plate formed with small holes at the tip end of the fuel injection valve. For example, as disclosed in the specification of U.S.Patent No.5,383,607, concave portions are formed at the needle tip end. Under such a configuration as above, although the auxiliary fine particle forming means could be eliminated, the flow or eddy of fuel might be generated along the concave portions at the tip end until the fuel reached the small holes in a direction opposite to the injection flowing direction, resulting in that smooth flow of fuel might be prevented and the internal energy of the fuel is lost and a sufficient atomization cannot be obtained. Also, in the above specification, the needle tip end is made flat in perpendicular to an axial direction of the needle. However, according to the above structure, since the fuel flowed axially while being expanded between the needle tip end surface and the orifice plate, its internal energy is lost and a sufficient atomization cannot be attained. Document JP 04 050464 A shows a fuel injector including a jet nozzle and an orifice plate being fixed to the jet nozzle by welding at the circumference thereof. In this device, the flow of fuel is directed from the valve sealing seat toward an orifice of the orifice plate in a straight manner. This means that the flow passage from a valve chamber (9) disposed upstream of the valve sealing seat to the orifice plate is inclined with respect to a longitudinal valve axis. SUMMARY OF THE INVENTION It is an object of the present invention to provide a fluid injection nozzle for atomizing fuel with a simple structure in view of the phenomenon in which disturbance of the fuel caused by fuel flow collision just before the injection have much influence on the fuel atomization. According to the fluid injection nozzle of the present invention, a pitch DH between the orifices at the inlet surface in the orifice plate (hereinafter called as a downstream direction control plate) and a seat diameter DS have a relation of 2 < DS/DH < 4 so that when the needle adopted to abut on the valve seat of the valve body is moved away from the valve seat, fluid flows into a spacing chamber defined and formed by the tip end surface of the needle tip end, the inner wall surface of the valve body, and the inlet surface of the orifice plate. Then, the main flow is changed in its direction by the orifice plate, the flow is U-returned back with the flow directed directly toward the orifice and the opposed flow at the center of the orifice plate while passing between the orifices, and a flow directed toward the orifice is produced, as a result, the flow directed toward the orifice can be uniformly produced. Also there is a relation of h < 1.5 d between the distance "h" in a needle axial direction and the diameter "d" of the orifice when the needle valve is open between the tip end surface disposed at the position opposing against the orifice and formed at the needle tip end and the orifice plate, and further there is a relation of H < 3d between the distance "H" ranging from the seat portion to the orifice plate inlet surface and the orifice diameter "d", so that a fluid flow passage between the tip end surface and the flow direction control plate can be made flat, a flow passing along the flow direction control plate can be produced and a concurrent collision of fuel flows just above the orifice can be induced. Accordingly, the atomization of the fluid injected from the orifice plate is facilitated for its fine particles due to the disturbance by the collision and a fuel atomization having a directional characteristic can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS Additional objects and advantages of the present invention will be more readily apparent from the following detailed description of the preferred embodiments thereof when taken along together with the accompanying drawing in which: FIG. 1 is an enlarged cross sectional view for showing an injection nozzle part of a fuel injection valve of a first embodiment of the present invention; FIG. 2 is a longitudinal cross section for showing the fuel injection valve of the first embodiment of the present invention; FIG. 3 is a cross sectional view for showing the injection nozzle part of the fuel injection valve of the first embodiment of the present invention; FIG. 4 is a cross sectional view taken along a line IV-IV of FIG. 3; FIG. 5 is an illustrative view for showing a fuel injection state of a two-directional injection system; FIG. 6 is a cross sectional view for showing an injection nozzle portion of a fuel injection valve of a second embodiment of the present invention; FIG. 7 is a cross sectional view taken along a line VII-VII of FIG. 6; FIGS. 8A-8C are graphs for showing an effect for atomized fuel having fine particles of the present invention; FIG. 9 is a schematic figure for showing a flow of fluid in a first comparison example; FIG. 10 is a schematic figure for showing a flow of fluid in a second comparison example; and FIG. 11 is a schematic figure for showing a flow of fluid in both the first embodiment and the second embodiment of the present invention. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to the drawings, preferred embodiment of the present invention will be described as follows. A first embodiment in which the present invention is applied to a fuel injection valve of a fuel supplying device of a gasoline engine is described with reference to FIGS. 1 to 5. At first, referring now to FIG. 2, a fuel injection valve as a fluid injection nozzle will be described. As shown in FIG. 2, a stationary core 21, a spool 91, an electromagnetic coil 32, a coil mold 31 and metallic plates 93, 94 for forming a magnetic path are integrally formed inside a resin housing mold 11 for a fuel injection valve 10 as a fluid injection nozzle. The stationary core 21 is made of ferromagnetic material and this iron core is arranged within the housing mold 11 in a manner as to protrude out of an upper portion of the coil mold 31. To an inner wall of the stationary core 21 is fixed an adjusting pipe 29. The electromagnetic coil 32 is wound around an outer circumference of a resin spool 91 and then the coil mold 31 made of resin is molded at an outer circumference of the spool 91 and an outer circumference of the electromagnetic coil 32, and the electromagnetic coil 32 is surrounded by the coil mold 31. The coil mold 31 is comprised of a cylindrical cylinder portion 31a for protecting the electromagnetic coil 32, and a protruding portion 31b for protecting a lead wire electrically led out of the electromagnetic coil 32 and protruding upwardly from the cylindrical portion 31a for holding a terminal 34 to be described later. Then, the spool 91 and the electromagnetic coil 32 are installed at the outer circumference of the stationary core 21 while being integrally assembled with the coil mold 31. Each upper ends of the two metallic plates 93 and 94 contacts with an outer circumference of the stationary core 21 and each lower ends contacts with an outer circumference of a magnetic pipe 23 so as to form a magnetic path for flowing a magnetic flux when the electromagnetic coil 32 is electrically energized. These plates 93 and 94 cover the outer circumference of the cylindrical portion 31a in such a manner that the cylindrical portion 31a is held from both sides. The electromagnetic coil 32 is protected by the two metallic plates 93 and 94. Above the housing mold 11 is arranged a connector portion 11a protruding out of an outer wall of the housing mold 11. Then, the terminal 34 electrically connected to the electromagnetic coil 32 is embeded in the connector portion 11a and the coil mold 31. In addition, the terminal 34 is connected to an electronic control device (not shown) through a wire harness. One end of a compression coil spring 28 abuts on an upper end surface of a needle 25 welded and fixed to a movable core 22, and the other end of the compression coil spring 28 abuts on a bottom portion of the adjusting pipe 29. The compression coil spring 28 biases the movable core 22 and the needle 25 in a downward direction as viewed in FIG. 3 to make a seat portion of the needle 25 be seated on a valve seat 263 of a valve body 26. When an exciting current flows from the terminal 34 to the electromagnetic coil 32 through a lead wire by an electronic control device (not shown), the needle 25 and the movable core 22 are retracted toward the stationary core 21 against a biasing force of the compression coil spring 28. A non-magnetic pipe 24 is connected to the lower portion of the stationary core 21. Then, to the lower portion of the stationary core 21 is connected one end 24a in a manner as to partially protrude from the lower end of the stationary core 21. In addition, to the lower end of the other end 24b of the non-magnetic pipe 24 is connected a diameter reduced portion 23b of the magnetic pipe 23 made of magnetic material and formed in a stepped pipe shape. The other end 24b of the non-magnetic pipe 24 may act as a guiding portion for the movable core 22. Then, within the inner spaces of the non-magnetic pipe 24 and the magnetic pipe 23 is arranged the movable core 22 made of magnetic material and formed into a cylindrical shape. An outer diameter of the movable core 22 is set to be slightly smaller than an inner diameter of the other end 24b of the non-magnetic pipe 24, and the movable core 22 is slidably supported at the non-magnetic pipe 24. The upper end surface of the movable core 22 is arranged in opposition to the lower end surface of the stationary core 21 so as to form a predetermined clearance. At the upper portion of the needle 25 is formed a connecting portion 43. Then, the connecting portion 43 and the movable core 22 are welded by laser, and the needle 25 and the movable core 22 are integrally connected. At the outer circumference of the connecting portion 43 are formed with two chamfered portions for forming fuel passages. Above the stationary core 21 is arranged a filter 33 for removing foreign materials such as dusts in fuel pressurized and supplied by a fuel pump or the like and flowing into the fuel injection valve 10. Fuel flowing into the stationary core 21 through the filter 33 passes from the adjusting pipe 29 through a clearance at the two chamfered portions formed at the connecting portion 43 of the needle 25 and further passes through a clearance at the four chamfered portions formed between a cylindrical surface 261 of the valve body 26 and a sliding portion 41 of the needle 25, reaches a valve portion comprised of a seat (abutting portion) 251 at the tip end of the needle 25 and a valve seat 263 and finally reaches a cylindrical surface 264 forming an injection hole from the valve portion. Referring to FIG. 3, a structure of a discharging portion 50 of the fuel injection valve 10 is described. The valve body 26 is inserted into a large-diameter portion 23a of the magnetic pipe 23 through a hollow disk-like spacer 27 and welded thereto by laser. A thickness of the spacer 27 is adjusted in such a manner that an air gap between the stationary core 21 and the movable core 22 shown in FIG. 2 is held with a predetermined value. FIG. 3 shows a closed valve state, wherein an inner wall of the valve body 26 is formed with a cylindrical surface 261 where a sliding portion 41 of the needle 25 slides and with a valve seat 263 on which a cylindrical abutting portion 251 of the needle 25 is seated. In the valve closed state, the abutting portion 251 and the valve seat 263 form a contact point and a set of such contact points is formed in an annular shape with a predetermined seat diameter DS. In addition, a cylindrical surface 264 is formed at a central bottom portion of the valve body 26. The needle 25 is formed with a flange 36 in opposition to a lower end surface of the spacer 27 accommodated in the inner wall of the large-diameter portion 23a of the magnetic pipe 23 so as to form a predetermined clearance. This flange 36 is formed at a side of the abutting portion 251 formed at the tip end of the needle 25 in the entire length of the needle 25, and further a lower portion of the flange 36 is formed with a sliding portion 41 which can slide on the cylindrical surface 261 formed at the valve body 26. A spacing chamber 84 is formed at a side of the tip end of a flat surface 82 as a tip end surface of the needle 25. The spacing chamber 84 is defined by shapes and positions of the needle 25, the valve body 26 and the orifice plate 52 and a combination of these elements as shown in FIGS. 1, 3 and 4. Each of these features will be described in sequence as follows. (1) Needle 25 As shown in FIG. 1, the tip end of the needle 25 is comprised of a solid cylindrical surface 61, an annular curved surface 81 and a flat surface 82. The annular curved surface 81 connects the flat surface 82 at the tip end of the needle 25 with the solid cylindrical surface 61 and can abut on a conical slant surface 262 of the valve body 26 at a portion which is formed in an annular shape having an arcuate cross section. The state shown in FIG. 1 indicates a valve open state, wherein the flat surface 82 is formed in parallel to be opposite against an inlet surface 52a of the orifice plate 52. In addition, an axial distance h of the needle, when the needle valve is open, between the flat surface 82 of the needle 25 and the inlet surface 52a of the orifice plate 52 is set to be smaller than 1.5 times of the diameter d of each of the orifices 54, 55, 56 and 57 to be described later. in this way, when the needle 25 is moved away from the conical slant surface 262 of the valve body 26, fuel flows in a clearance between the annular curved surface 81 and the conical slant surface 262 toward the orifice plate 52 and collide with the inlet surface 52a of the orifice plate. Then, the fuel is curved in a direction toward a spacing chamber partitioned by the conical surface 262 at the inlet side of the orifice plate 52, the flat surface 82 and the inlet surface of the orifice plate 52 and flows along an inlet port surface of the orifice plate 52. That is, the fuels flows directly toward the orifice, further passes by the orifices and returns back in a U-shape at a center of the orifice plate with an opposing flow so that fuel is directed toward the orifice. Thereby fuel collides with each other just above the orifice so as to make an unstable flow state and the atomization of the fuel is facilitated. That is, since the aforesaid distance h and 1.5 times of the aforesaid diameter d are set to have a relation of h < 1.5d, it is possible to flow fuel in a narrow clearance between the flat surface 82 and the inlet surface of the orifice plate 52 and thus to induce a collision of the flows to each other in a direction perpendicular to the orifice. In this way, it is possible to increase colliding energy of the fuels from each other and to facilitate the atomization of the fuel. (2) Valve Body 26 The valve body 26 is comprised of a cylindrical surface 261, a conical slant surface 262 as an inclined surface of the inner wall surface of which diameter is reduced toward a flowing direction of fluid and a cylindrical surface 264 forming a cylindrical hole, wherein boundary lines of each of these surfaces 261, 262 and 264 are circular. A valve seat 263 formed at the conical slant surface 262 is placed at a position where the abutting portion 251 of the needle 25 can abut. A distance H between the valve seat 263 and the orifice plate 52 is set to have a relation of H < 3d in respect to the diameter d of the orifice to be described later. That is, the valve seat acting as the inlet for fuel to the spacing chamber is disposed at a place near the orifice plate. In this way, when the needle 25 and the valve body 26 are spaced apart, it is possible for the fuel flowing between the abutting portion 251 and the valve seat 263 into the spacing chamber along the conical slant surface 262 to flow along the inlet surface of the orifice plate. The cylindrical surface 264 is formed between the needle 25 and the orifice plate 52 at the inlet side of the orifice plate 52 in such a range as not to have an influence on main flow. (3) Orifice Plate 52 The orifice plate 52 acting as an orifice plate for controlling a flow direction of atomization is made of stainless steel and connected to a tip end of the valve body 26 as shown in FIGS. 3 and 4 by welding such as welding at an entire circumference. This orifice plate 52 has orifices 54, 55, 56 and 57 having equal four diameters d in a direction of plate thickness. (i) Inclination angle of the orifice As shown in FIG. 4, there are four orifices 54, 55, 56 and 57, and each of these orifices 54, 55, 56 and 57 is formed in a straight cylindrical shape, and a central axis of the cylinder and the orifice side walls 54a, 55a, 56a and 57a are inclined only by the inclination angles α1,α2 in a direction more far from the center than the plate thickness direction as shown in FIG. 4. Fuel passing through the orifices 54, 55, 56 and 57 is accurately injected along the inclination angles α1, α2. Herein, α1 in this case is defined as an inclination angle as viewed from the orifices 55, 56 toward the orifices 54, 57 and α2 is defined as an inclination angle as viewed from the orifices 54, 55 toward the orifices 57, 56, respectively. This embodiment discloses double-direction atomization. For example, as illustrated in FIGS. 4 and 5 and as described later, a fuel flow F1 is injected from the orifices 54 and 55 toward the bevel portion of one intake valve 102 and a fuel flow F2 is injected from the orifices 57 and 56 toward the bevel portion of the other intake valve 101. The inclination angles α1, α2 of the orifices 54, 55, 56 and 57 have preferably a range of 10 ≦α1, α2≦40 (° ) and the values of α1, α2 are properly set in compliance with the specification of the engine. (ii) position of the orifice As shown in FIG. 1, each of the orifices 54, 55, 56 and 57 is set such that a pitch of each of the orifices at the inlet surface of the orifice plate 52 is set to be ⊘DH and all the opening surfaces 54b, 55b, 56b and 57b for the spacing chamber are positioned within an imaginary envelope (with a diameter of (⊘D2)) formed by a crossing line between an extended plane of the conical slant surface 262 of the valve body and an inlet surface of the orifice plate 52. That is, there is a relation of ⊘D1 < ⊘D2 between the diameters of ⊘D1 and ⊘D2 of the envelopes of four orifices. In addition, the diameter ⊘Ds of the needle seat and the inter-orifice pitch ⊘DH are set to have a relation of 2 < DS/DH < 4 Accordingly, in the case that the needle 25 and the valve body 26 are spaced apart from each other, fuel flowing between the abutting portion 251 and the valve seat 263 into the spacing chamber flows along the conical slant surface 262, thereafter its flowing direction is changed by the inlet surface 52a of the imaginary envelope of the orifice plate 52 and then the fuel flows by a predetermined distance between the inlet port 52a of the orifice plate 52 and the flat surface 82. Accordingly, the main flow of the fuel can be efficiently atomized without flowing directly into the orifices 54, 55, 56 and 57. In addition, in view of the aforesaid relation, an intensity of the fuel flow can be equalized in respect to its flowing direction for each of the orifices 54, 55, 56 and 57, respectively. As to a reason for this effect, the present inventors have confirmed it through experiment of visualization, which is described through the first comparison example in reference to FIG. 9. In this first comparison example, the value of DS/DH is set to have a range which is larger than a value of 4 or lower of a numerical limitation range of the present invention. In FIG. 9 is illustrated a flow of fuel before passing through the orifice of the first comparison example in which four orifices are arranged in respect to the center of the disc-like orifice plate 52 in relation of DS/DH = 4.4 inter-orifice pitch DH =⊘0.7 and a seat diameter of the needle is defined as DS =⊘3.1. A part of the flow directed from the outer circumference of the orifice plate is bent at its center and another portion directly flows to the orifice. In this case, the orifice pitch DH is small in respect to the needle seat diameter DS, i.e. four orifices are formed concentrically only at the center portion of the needle, so that the flow directed toward the orifice after being bent at the center of the plate is weaker than that directed from the outer circumference of the orifice plate to the orifice, and therefore, a uniform collision cannot be obtained. To the contrary, in the case that the four orifices are arranged to have a relation of 2 < DS/DH < 4 as in the first embodiment, the four orifices are formed at dispersed locations spaced apart from the center of the needle, so that a difference in intensity between the flow directed toward the orifices after being bent at the center and the flow directed from the outer circumference of the orifice plate to the orifices directly can be reduced and a uniform collision can be obtained. (iii) Arrangement of the Orifices In addition, each of the four orifices 54, 55, 56 and 57 is arranged at each of the peak points of a square. In this way, it is possible for the fuel to pass smoothly from the spacing chamber through the orifice and to be injected therefrom. Since the present inventors have confirmed the reason for it through a visualization experiment, which is described in reference to FIGS. 10 and 4. In FIG. 10 is illustrated a flow of fuel before passing through the orifices of the second comparison example (in this second comparison example, it is set to be a larger range than that of the numerical limitation range of the present invention of 0.9 < b/a < 1.1) in which four orifices are arranged at peak points of a rectangle with its center being placed at a center of a disc-like orifice plate, its one side length a being 1 and a length "b" of the adjacent side being 2.22 (a ratio between a longitudinal side and a lateral side being 2.22). FIG. 10 shows one of the four segments in which the orifice plate is equally divided into the four segments. A flow directed from the outer circumference of the orifice plate toward its center is partially U-turned back by a counter flow at its center and toward the orifice and further partially flows directly toward the orifice. In this way, the flow of fuel directed from the outer circumference of the orifice plate toward the orifices as shown in FIG. 10 has a pitch differing from that of the adjacent orifice. Accordingly, an amount of flowing line directed toward each of the orifices may produce an eccentric flow in reference to a flowing direction, thus losing a uniform flow and may produce an eddy flow of a counter-clockwise direction due to unbalanced fuel flow. To the contrary, in the case that the four peak points of a square with b/a = 1 (a vertical and lateral ratio of 1.00) have four orifices arranged as in the first embodiment shown in FIG. 4, it is possible to reduce an occurrence of surplus eddy in the fuel flowing into the orifices and thus it is possible to strike the fuels from each other just above the orifices. That is, in the first embodiment, the orifices are placed at the peak points of the square and arranged to have a relation of 2 < DS/DH < 4 can be obtained. In FIG. 11 is shown a state of fuel flow at that time. The flow of fuel flowing into the orifices flows toward the center of the orifices without producing any eddy current around the orifices. In addition, it is possible to reduce a difference between an intensity of flow flowing into the orifices after U-turned with opposing flows at the center of the orifice plate and an intensity of flow flowing from the outer circumference of the orifice plate directly to the orifices (isotropic flow) and to collide with each other equally at the center of inlet of the orifice. In this way, a more efficient utilization of internal energy of fuel can be obtained in a form of disturbance of fuel caused by collision of the flows with each other, and therefore, a quite rational atomization can be realized. In addition, since a uniform collision of the flows can be obtained at the center of the inlets of the orifices, atomization having a quite superior directional characteristic can be obtained along a slant of the entire circumference of the side wall of the orifice. FIG. 8 shows a graph in which each of the values of DS/DH, 1.5d - h, and 3d - H is indicated at an axis of abscissas and a degree of the atomization is indicated at an axis of ordinates, respectively. A degree of the atomization is expressed by an SMD (Sauter Mean Diameter, i.e. Sauter mean particle diameter). Each of the values of SMD within a range of 2 to 4 of DS/DH in FIG. 8A, a range of more than 0 of a value of 1.5d - h (mm) in FIG. 8B, and a range of more than 0 of 3d - H (mm) in FIG. 8C is 100µm or less. As can be apparent therefrom, a superior atomization can be realized. In the first embodiment, the present invention is applied to the two-directional injection system as shown in FIG. 5. Such a two-directional injection system is briefly described in reference to FIG. 5. As shown in FIG. 5, intake valves 101, 102, which are opened and closed, are fixed at an intake port 162 and an intake port 163 open into a combustion chamber of an engine 160. Between the intake port 162 and the intake port 163 is formed a wall member 164 for partitioning both ports. The fuel injection valve 10 is fixed in such an orientation as one in which the fuel is injected toward the bevel portions of the intake valves 101 and 102. According to the first embodiment, in the case that the needle 25 and the valve body 26 are spaced apart from each other, a part of the fuel flowing from the entire circumference toward a center of the orifice plate is changed in its direction between the center 82a of the needle and the inlet surface 52a of the orifice plate. Then, the fuel flows toward the orifice and collides with the fuel flowing from the outer circumference of the orifice plate at the center of the orifice inlet. In addition, since it is possible to for the fuel to collide just above the orifice without produce any eddy flow, the internal energy of the fuel can be taken out efficiently as a disturbance caused by the collision and an efficient atomization can be realized. In addition, since an intensity of fuel flowing into the orifice after being U-turned at the center of the orifice plate is approximately the same as that of a fuel flowing from the outer circumference of the orifice plate to the orifice, a uniform collision can be obtained without producing any eddy flow at the circumference of the orifice, and a more efficient atomization can be realized. Concurrently, the fuel collides with each other at the center of the orifices and a uniform collision of the fuel can be obtained, so that the directional characteristics of the atomized fuel is controlled by the side walls 54a, 55a, 56a and 57a of the orifice. A second embodiment of the present invention is described with reference to FIGS. 6 and 7. In the second embodiment shown in FIG. 6, a solid cylindrical surface 61, a conical slant surface 62 and an annular curved surface 81 are formed at the tip end of the needle, and the tip end is formed with a smooth conical surface 83 as a tip end surface of which diameter is reduced as it is directed toward the center of the needle. Then, a crossing line between the cylindrical portion 61 and the conical slant surface 62 of the needle 25 forms an abutting portion 251, and a distance H between a valve seat 263 of the valve body 26 and the inlet surface 52a of the orifice plate is H = 0.4 mm. A taper angle γ of a taper surface is set to γ= 5° , a distance "t" between the center 82a of the tip end of the needle and its opposing inlet surface 52a of the orifice plate is set to t = 0.1mm; a lifting amount "p" of the needle 25 is set to p = 0.06 mm; a diameter "d" of each of the orifices 54, 55, 56 and 57 is set to d = 0.25 mm; an inter-orifice pitch DH is set to DH = 1.05 mm; inclination angles α1, α2 of the orifices are set to α1 = 15° and α2 = 5° ; a seat diameter DS is equal to a needle diameter, i.e., DS = 3.1 mm; and a slant surface angle β of the body valve 26 is set to β = 50° , respectively. Accordingly, a vertical line distance between the center 82a of the tip end of the needle and its opposing orifice plate inlet surface 52a when the valve is open, i.e. t + p = 0.16 mm is set. Then, the tip end of the needle end is formed with a smooth conical surface in such a manner that its outer circumference has a more enlarged axial needle distance h (a vertical line distance) up to the orifice plate. Then, the conical surface having as its center the tip end center 82a at the tip end surface of the needle is set so as to satisfy a relation of h < 1.5d (= 0.375 mm) between a vertical line distance h up to the orifice plate inlet surface when the needle valve is open and the orifice diameter d over its entire region, and a distance H = 0.4 mm is smaller than three times of the orifice diameter d = 0.25mm and a relation of H < 3d. In addition, the value of DS/DH (= 3.1/1.05 = 2.95) is set between 2 and 4. Accordingly, also in the second embodiment of the present invention, it is possible for the fuel to flow in the narrow clearance between the conical surface 83 and the inlet surface 52a of the orifice plate 52 in the same manner as that of the first embodiment, thereby making is possible to induce collision of fuels to each other in a direction perpendicular to the orifice. In addition, it is also possible for a flowing-in angle of fuel flowing from between the abutting portion 251 and the valve seat 263 along the conical slant surface 262 into the spacing chamber 84 to be closer the inlet surface of the orifice plate. Further, the orifices 54, 55, 56 and 57 are arranged at positions where main major flow of fuel does not directly flow into the orifice, so that the fuel can be efficiently changed into fine particles. Also in the second embodiment, the orifices 54, 55, 56 and 57 have the angles α1, α2 which are similar to those of the first embodiment and positions thereof are also located at the same positions as those of the first embodiment, so that no eddy flow is produced around the orifice and the fuels can uniformly collide with each other at the center of the orifice inlet, resulting in that superior atomized fuel in quite superior fine particle formation and directional characteristic can be obtained (since its detailed description is the same as that of the first embodiment, its description is omitted herein). In the second embodiment, it is set that DS/DH = 2.95 and 3d - H = 0.3 (mm) > 0 in FIG. 7 and 1,5 d - h > 0 (mm), so that the fuel flow can be set approximately to 90 µm. In addition, the injection flows passing through the orifices 54, 55 and 56, 57 are set such that pitches thereof are enlarged by the aforesaid inclination angles α1, α2 in FIG. 7 in respect to a flowing-out direction of the injection flows. In this way, atomized fuel passing through the orifices 54, 55 are injected while maintaining superior fine flow without damaging fine particles by interfering atomized particles so as to join together. Atomized fuel injected through the orifices 56, 57 are same as well. In addition, in the second embodiment, since the tip end surface of the needle is formed into a smooth conical surface 83, it is easy to machine the tip end, thus being advantageous in manufacturing. In the present invention, the number of orifices formed in the orifice plate for controlling a direction of atomization is not limited to any number, but it may be of a plurality of numbers, and an inclination direction of each of the holes is not limited to any special angle. In addition, although a direction of fuel is controlled through the orifice plate, means for controlling the direction of fuel is not limited to a plate-like member if the member has a flat surface portion which guides the fuel to the orifice after the main flow of fuel collides with each other. Further, a sleeve-like member having partially the plate portion may be applied, and also another direction controlling plate may be applied. In addition, the two-directional injection has been described in the above embodiments, however, the present invention can also be applied to uni-directional injection system. In this case, there is a relation of α1 = α2 between the orifice inclination angles α1 and α2 and a uniform flow of fuel is injected through four orifices or a plurality of orifices other than 4. In addition, in the first and second embodiments, the tip end of the needle is entirely formed except the annular curved surface, however, the range of the tip end surface is not limited thereto, but if the tip end of the needle is disposed at a position opposing against the orifice, it may be formed at a part of the tip end. In addition, it is preferable that the diameter "d" of the orifice is equal to 0.25mm or more than that as disclosed in the second embodiment. For example, if the number of orifices is too large and the diameter d is too small, it becomes difficult to keep a clearance between the needle and the orifice plate small and a desired atomization having fine particles may not be easily obtained. According to the fluid injection nozzle of the present invention, it is possible to obtain a plurality of atomized flows having a superior accurate directional characteristic and changed into fine particles through the flow direction control plate with a simple configuration. In this way, it is possible to provide a fuel injection valve capable of getting a superior fuel atomization in which the fuel can be directed toward a bevel portion of the intake valve and easily mixed with air, thus improving an exhaust emission and further reducing an amount of fuel consumption. Although the present invention has been fully described in connection with the embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications will become apparent to those skilled in the art. Such changes and modifications are to be understood as being included within the scope of the present invention as defined in the appended claims.

Claims: A fluid injection nozzle comprising: a valve body (26) having an inner wall surface (262) for forming a fluid passage therein and a valve seat (263); a needle (25) disposed in said fluid passage and having an abutting portion with a predetermined annular seat diameter, said abutting portion (251) being adopted to abut on or move away from said valve seat (263), for intermittently performing a fluid injection, said needle being formed at a downstream tip end thereof and inside said abutting portion (251) and having a tip end (82) at a position opposite to said orifice (52); and an orifice plate (52) fixed to said valve body (26) at a downstream side of said inner wall surface (262) of said valve body (26) and having a plurality of orifices (54, 55, 56, 57) for passing fluid in a plate thickness direction ; characterized by the following dimensional relationships: 2 < DS/DH < 4, h < 1.5d, and H < 3d where a diameter of said orifice is d, a pitch between said orifices (54, 55, 56, 57) at the inlet port surface (52a) of said orifice plate is DH, said predetermined seat diameter is DS, a distance ranging from said valve seat (263) to said orifice plate inlet surface (52a) is "H", and a vertical line distance ranging from said tip end surface (82) to said orifice plate inlet surface (52a) opposite against said tip end surface (82) when said abutting portion (251) is spaced apart from said valve seat (263) is h; such that the main flow of fluid at the downstream side of said abutting portion (251) is formed in such a manner that fluid collides with each other just above the orifices so as to make an unstable flow state in order to facilitate atomization of fluid. A fluid injection nozzle according to claim 1, wherein said inner wall surface (262) has an inclination surface of which diameter is reduced toward a direction of flow of fluid. A fluid injection nozzle according to claim 2, wherein said inner wall surface (262) is a conical inclination surface. A fluid injection nozzle according to claim 3, wherein said tip end surface (82) is disposed at a center of said downstream side tip end. A fluid injection nozzle according to claim 4, wherein said tip end surface (82) is formed substantially in parallel with said inlet surface (52a) of said orifice plate (52). A fluid injection nozzle according to claim 5, said plurality of orifices (54, 55, 56, 57) are four in number. A fluid injection nozzle according to claim 6, wherein said four orifices (54, 55, 56, 57) are placed at peak point positions of a rectangle having the following relationship: 0.9 < b/a < 1.1 where one side length of said rectangle is "a" and another adjacent side length is "b". A fluid injection nozzle according to claim 7, wherein said four orifice (54, 55, 56, 57) are inclined by a predetermined angle in respect to said plate thickness direction. A fluid injection nozzle according to claim 8, wherein said predetermined angle is in a range of 2° to 40° in a direction spaced apart from the center of said imaginary envelope line. A fluid injection nozzle according to claim 9, wherein a fuel injection flow F1 in one direction is formed by two orifices (54, 55) of said four orifices and a fuel injection flow F2 in another different direction is formed by the other two orifices (56, 57). A fluid injection nozzle according to claim 10, wherein each of said fuel injection flow F1 and said fuel injection flow F2 is injected toward a different intake valve. A fluid injection nozzle according to claim 9, wherein a single directional fuel injection flow is formed by said four orifices (54, 55, 56, 57). A fluid injection nozzle according to claim 4, wherein said tip end surface (82) is a smooth conical surface of which diameter is gradually reduced toward a fluid flowing direction. A fluid injection nozzle according to claim 13, wherein said plurality of holes are four orifices (54, 55, 56, 57). A fluid injection nozzle according to claim 14, wherein said four orifices (54, 55, 56, 57) are disposed at peak point positions of a square. A fluid injection nozzle according to claim 15, wherein said four orifices (54, 55, 56, 57) are inclined by a predetermined angle in respect to a fluid direction. A fluid injection nozzle according to claim 16, wherein in that said predetermined angle is in a range of 2° to 40° in a direction moving away from a center of said imaginary envelope line. A fluid injection nozzle according to claim 17, wherein one directional fuel injection flow F1 is formed by two orifices (54, 55) of said four orifices and another directional fuel injection flow F2 is formed by the other two orifices (56, 57). A fluid injection nozzle according to claim 18, wherein each of said fuel flow F1 and said fuel flow F2 is injected toward a different intake valve. A fluid injection nozzle according to claim 17, wherein uni-directional fuel injection flow is formed by said four orifices (54, 55, 56, 57).

Inventors: MORI YUKIO, TANI YASUHIDE, MORI, YUKIO, TANI, YASUHIDE
Applicants: DENSO CORP, DENSO CORPORATION
Application year: 1996
Main classification: F02M61
IPC codes: F02M51, F02M61