ELECTROMAGNETIC FUEL INJECTION VALVE

Abstract: An electromagnetic fuel injection valve (1) includes a fuel swirl element (13) disposed upstream of a valve seat (9) for giving a swirl force to fuel, a fuel injection port (8) disposed downstream of the valve seat (9), fuel dividing device (16) disposed downstream of the fuel injection port (8) for dividing a fuel flow.

Description: The invention relates to an electromagnetic fuel injection valve according to the first portion of claim 1 capable of supplying fuel to a multi-valve engine in which each cylinder has a plurality of intake valves. An electromagnetic fuel injection valve for use in a multi-valve engine in which each cylinder thereof has two intake valves is disclosed in the US-A-4 657 189 (= JP-A-61/152 765). Said injection valve includes a fuel dividing portion disposed downstream from a single injection hole which performs the metering of fuel, this fuel dividing portion being capable of dividing fuel to be injected from said injection hole. Two branch passages are disposed inclined with respect to the axis of the injection valve. The main passage disposed upstream of the fuel dividing portion is disposed upstream of the point at which the inner walls of the branch passages meet and the shape of the point is designed to have an acute angle so that the fuel injecting angle and the fuel distribution to each of the branch passages are respectively made to correspond to predetermined values. In said known injection valve the accuracy can be improved such as to make uniform the fuel distribution from the main passage to the branch passages and to make the amount of fuel distribution be a predetermined value. In addition, the metering accuracy can be improved since the flow of fuel through the main passage is stabilized. On the other hand, since the shape of the fuel stream atomized from the single injection hole is a bar-like shape, the thickness of the fuel particles after passing through the main passage does not become small and it is difficult to make the mean particle diameter of the atomized fuel be 200 µm and below. Further, there is a problem that a portion of the atomized fuel which has been subjected to the restriction of the fuel direction dividing portion is combined with another portion of the atomized fuel which has not been subjected to the restriction, so that the particle diameter of the atomized fuel becomes large. The DE-U-87 09 111 discloses an electromagnetic fuel injection valve comprising a flat valve member, a valve seat, a fuel injection port disposed downstream of said valve seat, and leading means disposed downstream of said fuel injection port for forming an injecting fuel flow. Said leading means include a central opening and peripherical openings surrounding said central opening. On the enlarged downstream end of said openings leading sheets are provided for expanding the surface of the injected fuel flow. From US-A-4 360 161 it is known an electromagnetic fuel injector valve for a single inlet valve engine, in which a shiftable valve ball acts on a conical valve seat and swirl means are disposed upstream of the valve seat for generating a swirl motion of the fuel after lifting the valve ball. The swirled fuel flows through a cylindrical injection port disposed downstream of the valve seat. The US-A-4 699 323 discloses an electromagnetic fuel injector valve for a combustion engine with two inlet valves. A spherical valve member is fixed on the lower end of a stream. Downstream of the valve seat a plate is provided having a plurality of inclined injection ports of small diameter for generating a swirling motion of the injected fuel in a downstream disposed discharge passage of cylindrical shape. For dividing the injected fuel flow to the two inlet valves of the engine a dividing wall is formed as a part of the manifold between the inlet valves. An object of the invention is to provide an electromagnetic fuel injection valve for a multi-valve engine capable of distributing the fuel from the injection hole with a good efficiency and injecting the fuel with an excellent fine particle characteristics. This object will be solved according to the present invention by the features of claim 1 and 5, respectively. The fuel dividing means disposed downstream of the single fuel injection port is capable of dividing the swirl fuel injected from the single injection port to introduce into two large-diameter passages without resulting any loss and injecting the fuel from the outlet port of the dividing means with a desired angle of distribution. The fuel in the dividing means flows downward with swirled in the large-diameter fuel passage and during flowing, the swirling force thereof is enhanced. The so called flow loss resulted from the wall surface of the dividing means can be sufficiently compensated, so that making the fuel be in fine particles can be promoted. At the outlet of the dividing means, the fuel is distributed by the swirling force, so that a desired atomizing angle is formed. The angle can be optionally set by adjusting the eccentric amount (a distance between the center of the groove and axis of the injection valve) of the grooves of the fuel swirl element mounted upstream of the injection port. The particles of the atomized fuel is concentrated in two directions and does not exist along the axis of the injection valve. As explained above, since the swirled fuel from the injection port is effectively divided by the dividing means and it is prevented for fuel particles to combine with each other, the fine particle fuel jet is formed. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a vertical cross-sectional view of an embodiment of an electromagnetic fuel injection valve according to the present invention; Fig. 2 is a cross-sectional view taken along line A-A of Fig. 1; Fig. 3 is a view viewed from arrow III in Fig. 1 and in which a first embodiment of an adapter according to the present invention is illustrated; Fig. 4 is a chart for determining the shape and dimensions of the adapter; Fig. 5 is an enlarged view of an essential portion of the adapter; Fig. 6 is a view showing the flow of fuel in the adapter; Figs. 7 and 8 are views showing the state of fuel atomization; Figs. 9 and 10 are graphs showing results of experiments; Fig. 11 is a view showing a second embodiment of the adapter according to the present invention; Fig. 12 is a view showing a third embodiment of the adapter according to the present invention; Fig. 13 is a view showing a fourth embodiment of the adapter according to the present invention; Fig. 14 is a vertical cross-sectional view of another embodiment of the electromagnetic fuel injection valve according to the present invention; Fig. 15 is a view viewed from arrow XV in Fig. 14; Fig. 16 is a view showing a portion of an internal combustion engine in which an electromagnetic fuel injection valve according to the present invention is employed; Fig. 17 is a view showing a positional relationship between the fuel injection valve according to the present invention and the suction valve; Figs. 18, 19, and 20 are graphs showing comparison results between the performance of the electromagnetic fuel injection valve according to the present invention and that of a conventional electromagnetic fuel injection valve. DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described with reference to Figs. 1 to 10. Fig. 1 is a vertical cross-sectional view of an embodiment of an electromagnetic fuel injection valve 1 according to the present invention. This injection valve 1 acts to inject and supply fuel by opening and closing the seat portion thereof in response to ON-OFF signals of a duty calculated by a control unit (not shown). Electric signals are supplied to a coil 2 as pulse. When an electric current is passed through the coil 2, a magnetic circuit is formed by a core 3, a yoke 4 and a plunger 5 and the plunger 5 is attracted to the core 3. When the plunger 5 is moved, a ball valve 6 which is integrally formed with the plunger 5 is so moved as to be separated from a seating surface 9 of a valve guide 7. As a result, a fuel injection hole 8 (called "orifice" hereinafter) is opened. The ball valve 6 comprises a rod 10 connected to an end of the plunger 5 made of a magnetic material, a ball 11 which is welded to an end of the rod 10, and a guide ring 12 made of a non-magnetic material and secured to an upper opening portion of the plunger 5. When the thus-formed ball valve 6 is moved, it is guided by both the guide ring 12 and an inner surface of a cylindrical fuel swirl element 13 inserted into a hollow portion formed in the valve guide 7. An amount of stroke of the ball valve 6 is determined by a clearance between a receiving surface 10a in a neck portion of the rod 10 and a stopper 14. On the other hand, a cylinder portion 15 extending in a direction opposite to the seating surface 9 is formed in the valve guide 7. An adapter 16 serving as fuel dividing means is inserted and secured to the cylinder portion 15. Fig. 2 is a cross-sectional view taken along line II-II of Fig. 1 in which a fuel swirl element 13 for supplying fuel to the orifice 8 is illustrated. The fuel swirl element 13 is provided with axial grooves 13a and radial grooves 13b. In the embodiment, the axial grooves 13a are formed by cutting away four surfaces. These grooves 13a serve as fuel passages for fuel introduced in the axial direction. The fuel which has passed through the grooves 13a is then introduced into the grooves 13b and eccentrically introduced into the orifice 8, so that the fuel is given a so-called "swirl force". The amount of the swirl force is adjusted by an amount of eccentricity L. Fig. 3 is a view viewed from an arrow III in Fig. 1 and shows an adapter 16 which is a fuel dividing means. The adapter 16 includes a fuel passage 17 at the center thereof communicating with the orifice 8. The profile of the fuel passage 17 is determined by a cylindrical center hole 17a having a diameter slightly larger than that of the orifice 8 at the center thereof, two cylindrical holes 17b having a relatively large diameter and oppositely and equally spaced with respect to the center hole 17a and circumscribed walls 18 which circumscribe the cylindrical holes 17a and 17b and have a constant radius of curvature. The radius of curvature R of the circumscribed walls 18 is determined by the following equation (refer to Fig. 4). where: d is a diameter of the center hole 17a, r is a radius of the center hole 17a, D is a diameter of the cylindrical holes 17b, k is a ratio of the diameter of the circle 17a to the diameter of the circle 17b (=D/d), w is a distance between the centers of the cylindrical holes 17b. Fig. 5 is an enlarged view of an essential portion of the state in which the adapter 16 is mounted. The adapter 16 is secured under pressure to the cylinder portion 15 of the valve guide 7. That is, a so-called "metal flow" method is employed in which the outer surface of the adapter 16 is fitted within the groove 19 formed in the valve guide 7 in such a manner that the material of the adapter 16 is introduced in the radial direction thereof by plastic fluidization as to be secured by pressure realized by this metal flow method. Fuel injection supply performed by the injection valve 1 structured as described above will be described. Fuel is pressurized and adjusted by a fuel pump or a fuel pressure regulator (not shown), and is introduced into the electromagnetic injection valve 1 through an introduction passage 34 via a filter 33. Fuel then is passed through a lower passage 35 of the coil 2, outer circumference of the plunger 5, a gap between the stopper 14 and the rod 10 and the grooves 13a and 13b in the fuel swirl element 13 and is supplied to the seating portion in the swirling motion. When the injection valve 1 is opened, the thus-supplied fuel is injected into an intake manifold through the orifice 8. Then, the fuel flow in the adapter 16 according to the present invention will be in detail described with reference to Fig. 5 again and Fig. 6 which is a partially enlarged view illustrating the fuel passage 17 of the adapter 16. The swirled fuel injected from the orifice 8 collides with the wall of the center hole 17a having a diameter relatively larger than that of the orifice 8 and then flows to the cylindrical holes 17b by being guided by the circumscribed walls 18, so that swirling flows are generated in the cylindrical holes 17b, respectively. As a result, flow as designated by an arrow of Fig. 5 are generated. In the fuel passage 17, divided swirling flow are, as shown in Fig. 6, generated in the cylindrical holes 17b having a relatively larger diameter. The fuel flow which have passed through the adapter 16 is expanded at an outlet portion of the cylindrical portion 15, so that an atomization pattern as shown in Fig. 7 is formed. It has been observed that the fuel atomized by the embodiment of the injection valve of the invention is divided into two direction flow and the fuel particles included in the flow is fine. Fig. 8 is a side view of the flow pattern of the atomized fuel shown in Fig. 7. That is to say, fuel conically atomized from the single orifice 8 is effectively divided into two direction flow to be a flat atomization pattern including fine fuel particles by the adapter 16. The making the fuel be fine particles is promoted by the swirl flow by means of the fuel swirl element 13 which is sufficient to make up for the loss due to the surface flow along the wall of the adapter 16 and by the fact that the joining of the fuel particles is prevented by the effectively divided swirl flow. The fuel swirl force can be maintained even if the atmospheric conditions are in a low temperature state (-30°C) or in a low pressure state (-550 mmHg). Therefore, any particles having large diameters can be prevented from being generated. Figs. 9 and 10 are graphs showing an example of experiments conducted by the inventors. Fig. 9 is a graph showing a relation between the diameters of particle diameter of the atomized fuel and the ratio D/d of, where D represents the diameter of the cylindrical holes 17b having a relatively larger diameter and d represents the diameter of the center hole 17a of the adapter 16. As can be seen, the adapter 16 arranged such that D/d is 2 can make the fuel particles be a diameter substantially 100 µm. Fig. 10 is a graph showing a relationship between D/d and the angles of atomization of fuel. As can be seen, the angle with respect to the particle diameter of 100 µm becomes such that the outermost angle ϑo of the atomized fuel is substantially 35° while the angle in the widthwise direction is substantially 15°. Although described previously, the angle of the atomized fuel can be optionally changed by adjusting the swirl force of fuel or by determining the shape and dimensions of the adapter 16 as can be understood from Fig. 10. Fig. 11 is a view showing a second embodiment of the adapter serving as a fuel dividing means, and which is an enlarged view of a hole portion 21 in an adapter 20. The hole portion 21 includes parallel walls 22a arranged to be slightly larger than the diameter of the orifice 8. A distance between the walls opposing to each other corresponds to the diameter of the center hole 17a of the first embodiment and it is expressed by d in Fig. 11. The parallel wall 22a is arranged to have a length l (l ≦ 1/2 d₀) for the purpose of stably supplying the swirling flow to two large-diameter holes 22b (d1) oppositely and equally spaced with respect to the center of the adapter 20 and in parallel with each other even when the position of the adapter 20 does not perfectly meet the axial center of the injection valve 1. The large-diameter holes 22b and the parallel walls 22a are communicated with each other by communicating walls 23 each of which has a desired radius of curvature R₁. Also in the embodiment, the performance and effect similar to that obtained in the first embodiment can be obtained. Fig. 12 shows a third embodiment of the adapter 31 in which three large-diameter holes 24 are communicated with a hole 26 disposed at the axial center of the adapter and having a slightly larger diameter (d2) than that of the injection hole 8 by communicating walls 25 having a radius R₂ of curvature. Referring to this drawing, arrows designate the direction of the fuel flow. As is shown, the fuel atomized flow is divided into three directions. Fig. 13 shows a fourth embodiment of the adapter 32 in which four large-diameter holes 27 are provided. Two large-diameter holes 27 are respectively disposed on the right side and the left side of the adapter. Each of these large-diameter holes 27 is communicated with a center hole 30 disposed at the axial center of the adapter and having a slightly larger diameter (d3) than that of the injection hole 8 by communicating walls 28, 29 having radius R₃ and R₄ of curvature, respectively. Referring to this drawing, arrows designate the direction of the fuel flow. As is shown, the fuel atomized flow is divided into four directions. Fig. 14 shows another embodiment of the present invention wherein the same reference numerals as those shown in Fig. 1 represent the same components. An electromagnetic fuel injection valve 50 includes a fuel-measuring and swirling elements 52 mounted on a valve guide 51, that is to say, is of a type for injecting fuel in swirl motion downstream of a valve seat 53. Reference numeral 54 represents a swirl orifice comprising a plurality of small holes, 55 represents a fuel swirl chamber. The swirl orifice 54 is opened in the fuel swirl chamber 55 and are disposed diagonally to the axis of the valve. Reference numeral 56 represents an adapter mounted on the lower end of the opening formed in the fuel swirl chamber 55. Fig. 15 is a view viewed from an arrow XV in Fig. 14 in which only the portion concerning an adapter 56 is illustrated. As is similar to the first embodiment shown in Figs. 3 and 4, the adapter 56 includes a fuel passage 60 of which profile is determined by a cylindrical center hole 57 having a diameter slightly larger than that of the fuel swirl chamber 55, two large-diameter cylindrical holes 58 oppositely and equally spaced with respect to the center hole 57 and in parallel with each other and circumscribed walls 59 having a radius R₅ of curvature. Arrows shown in Fig. 15 designate the fuel flow. As is shown, the fuel is injected from the swirl orifice 54 disposed in the fuel measuring and swirling element 52 to the fuel swirl chamber 55 in which a swirl force is given thereto. The thus-swirled fuel reaches the fuel passage 60 of the adapter 56 in which the fuel is divided into two directions. Also in this embodiment, the fuel can be efficiently divided and the effect as same as the first embodiment can be obtained. Fig. 16 shows an engine control system on which the electromagnetic fuel injection valve 1 according to the present invention is mounted. Fig. 17 shows a state in which the electromagnetic fuel injection valve 1 is mounted. A DOHC (Double Over Head Camshaft) engine comprises two cam shafts for driving intake and exhaust valves whereby it is easily effected to make the engine high revolution and high power. In particular, in four-valve engines, an excellent combustion performance can be obtained since ignition can be conducted in the vicinity of the central portion of the combustion chamber. Furthermore, since a great amount of air can be sucked in the engine at a time, a significantly high response can be realized. The DOHC engines have a lot of merits as explained above. In Fig. 16, a DOHC engine 100 is shown. The engine 100 comprises an intake manifold 120 including a throttle valve 110, air intake ports 130, air intake valves 140 for opening and closing the air intake ports 130, a fuel combustion chamber 160 in which an ignition plug 150 is faced and the fuel injection valve 1 according to the present invention fixed to the wall portion of the air intake manifold 120 at the position upstream of the air intake valves 140 so that the fuel can be injected toward valve seats 140a of the air intake valves 140. Fig. 17 shows a positional relation between the fuel injection valve 1 and the air intake valve 10. The fuel is atomized in two directions and the fuel atomized in two direction are injected into the intake ports 130 by the injection valve 1 so as not to collide with a partition wall 140b which separates the intake ports 130. The operation of engine is controlled by a control unit 170 on the basis of the information of operation such as the water temperature of the partition wall of the fuel chamber 160, amount of suction air, air temperature, and engine speed and so on. The fuel injection from the fuel injection valve 1 is conducted in response to a signal transmitted from this control unit 170. A mixture gas of the fuel and air is introduced from the air intake hole 130 formed in the engine 100 to the combustion chamber 160 in which it is compressed during the compression stroke, and then the-thus compressed mixture gas is ignited and subjected to combustion with the ignition plug 150. Figs. 18 and 20 show results of experiments in which the fuel injection valve 1 according to the present invention is applied to the engine 100 of the type described above. In order to compare the performance, results of the experiments upon the conventional fuel injection valve (pintle valve) are illustrated together. Figs. 18 and 19 show results of experiments about the starting performance. As is apparent, the starting performance due to the injection valve of the invention is significantly improved. In particular, although the conventional pintle valve could not realize a complete fuel combustion when the atmospheric temperature was -30°C, the injection valve according to the present invention caused the initial combustion within several seconds and the complete combustion (range of pulse widths from 90 to 150 ms) within ten seconds. As the ruled value is within 20 seconds, in the injection valve of the invention, it is possible to set the width of the starting pulse to the degree of 70 msec which is about half of the conventional predetermined value and it is not needed to provide an injector for starting and it is possible to improve the fuel consumption. Fig. 20 shows a result of the acceleration responsibility test in which the rise of engine speed when the throttle valve was, in 0.15 seconds, opened fully from the idle state is compared. The fuel injection valve according to the present invention can cause the rise to be shortened by substantially 150 ms in comparison with the rise of the conventional pintle valve. This shows that the combustion just after the acceleration is extremely quickly effected and that the adhesion of fuel to the partition wall which separates the intake ports and the inner wall of the intake manifold can be avoided and that the fuel injection valve according to the present invention has a superior performance to atomize the fuel in fine particles. As described above, the fuel injection valve according to the present invention can provide various practical effects such as improvements in the fuel consumption, starting performance at low temperatures and accelerating performance. According to the invention, provided are electromagnetic fuel injection valves which have a superior atomization performance to atomize the fuel in fine particles and can divide the fuel from a single injection port into two or more directions effectively and therefore is suitable for the multi-valve engines.

Claims: An electromagnetic fuel injection valve comprising a movable valve member (11) acting on a valve seat (9), an injection port (8) disposed downstream of the valve seat (9), and fuel dividing means (16) disposed downstream of the injection port (8) for dividing the injected fuel flow, the fuel dividing means (16) including a fuel passage (17) defined by a centrical circle (17a) and at least two lateral circles (17b), the cross-sections of said circles (17a and 17b) perpendicular to the axis of the injection valve being disposed symmetrically with respect to said valve-axis, characterized in that a fuel swirl element (13, 54) giving a swirl force to the fuel is provided upstream of the valve seat (9), the diameters (D, d) of said circles (17a, 17b) are larger than the diameter of the fuel injection port (8), the diameter of the centrical circle (17a) is smaller than the diameter of the lateral circles (17b), and circular arcs (18, 23) circumscribe and connect said circles (17a, 17b). An electromagnetic fuel injection valve according to claim 1, characterized in that said fuel passage (17) is disposed in parallel with said fuel injection port (8). An electromagnetic fuel injection valve (1) according to claim 1 or 2, characterized in that the fuel swirl element (13) disposed upstream of a valve seat (9) is provided with axial grooves (13a) and radial grooves (13b) for eccentrically introducing the fuel into the injection port (8). An electromagnetic fuel injection valve according to claim 3, characterized in that the circular arcs (23) which circumscribe said plurality of circles (22b) have center points disposed away from each other by a distance (ℓ) smaller than the diameter (d) of said fuel injection port (8). An electromagnetic fuel injection valve (50) according to the first portion of claim 1, characterized in that a plurality of fuel injection ports (54) disposed downstream of the valve seat are inclined with respect to the axis of said injection valve (1), a fuel swirl chamber (55) is disposed downstream of the fuel injection ports (54) in which fuel which has been given a swirl force by said fuel injection ports (54) is swirled, and the dividing means (56) are disposed downstream of said fuel swirl chamber (55), said centrical circle (57) has a diameter slightly larger than that of the fuel swirl chamber (55), the diameters (D, d) of said circles (58) are larger than the diameter of the fuel injection ports (54), the diameter of the centrical circle (57) is smaller than the diameter of the lateral circles (58), and circular arcs (59) circumscribe and connect said circles (57, 58). An electromagnetic fuel injection valve according to claim 5, characterized in that the injection ports (54) and the swirl chamber (55) are disposed in a fuel measuring and swirling element (52) fixed on a valve guide member (51). An electromagnetic fuel injection valve according to claims 1 to 6, characterized in that the fuel dividing means (16; 56) are designed as an adapter fixed in the valve guide body (7) of the injection valve or in the fuel measuring and swirling element.

Inventors: HAMASHIMA, EIGI, KASHIWAYA, MINEO, NAKAMURA, YOZO, OKAMOTO, YOSHIO TSUKUBA HAUSU 14-103
Applicants: HITACHI AUTOMOTIVE ENGINEERING CO., LTD., HITACHI, LTD.
Application year: 1989
Main classification: F02M51
IPC codes: F02M61, F02M51