Fuel injection valve

Abstract

To provide a fuel injection valve capable of suppressing fuel separation on a lower end part side of an opening part of a valve seat.SOLUTION: A fuel injection valve comprises: a valve seat surface 15a2 with / from which a valve body 17 comes into contact and separates; a radial fuel passage 211 provided downstream of the valve seat surface 15a2 and allowing fuel to flow radially outward; a fuel introduction hole 15a3 provided downstream of the valve seat surface 15a2 and upstream of the radial fuel passage 211 and allowing fuel having flowed down the valve seat surface 15a2 to flow in an axial direction to introduce the fuel into the radial fuel passage 211; a fuel injection hole provided downstream of the radial fuel passage 211; and an enlarged diameter part 15c provided downstream of the fuel introduction hole 15a3 and enlarging in diameter toward the downstream side.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a fuel injection valve that injects fuel. [Background technology]

[0002] The fuel injection valve of Patent Document 1 has a valve seat portion composed of an upstream conical seat surface and a downstream conical tapered surface connected to the downstream end of the upstream seat surface, and satisfies α>β, where α is the angle between the seat surface and the central axis of the valve seat and β is the angle between the tapered surface and the central axis. Furthermore, the tapered surface is formed so that the intersection Y between the apex of an imaginary cone extending downstream from the tapered surface and the central axis is located downstream of the center of the opening of the valve seat (see abstract). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 230225 Summary of the Invention [Problem to be solved by the invention]

[0004] The fuel injection valve of Patent Document 1 has a seat surface and a tapered surface that satisfy α>β, and therefore has an effect of suppressing fuel separation at the upper end of the opening of the valve seat. However, the fuel injection valve of Patent Document 1 does not give sufficient consideration to fuel separation at the lower end side of the opening of the valve seat.

[0005] An object of the present invention is to provide a fuel injection valve capable of suppressing fuel separation on the lower end side of the opening of the valve seat. [Means for solving the problem]

[0006] In order to achieve the above object, the fuel injection valve of the present invention comprises: a valve seat surface to which the valve disc moves; a radial fuel passage provided downstream of the valve seat surface and configured to allow fuel to flow radially outward; a fuel introduction hole provided downstream of the valve seat surface and upstream of the radial fuel passage, for introducing fuel that has flowed down the valve seat surface into the radial fuel passage by causing the fuel to flow in an axial direction; a fuel injection hole provided downstream of the radial fuel passage; an expanded diameter portion provided at a downstream portion of the fuel introduction hole and expanding in diameter toward the downstream side; Equipped with. Effect of the Invention

[0007] According to the present invention, in the fuel injection valve, fuel separation on the lower end side of the opening of the valve seat can be suppressed. [Brief description of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view showing a cross section along a valve axis (central axis) 1a of a fuel injection valve 1 according to the present invention. [Diagram 2] 2 is an enlarged longitudinal sectional view (corresponding to the cross section taken along the line II-II in FIG. 3) showing the vicinity (nozzle portion) of a valve portion 7 and a fuel injection portion 21 of the fuel injection valve 1 shown in FIG. 1. [Diagram 3] 3 is a plan view of a nozzle plate 21n as seen from the direction of arrows III-III in FIG. [Figure 4] 4 is an enlarged plan view showing the swirl chamber 212 and the fuel injection hole 220 (an enlarged plan view of a portion IV shown in FIG. 3). FIG. [Diagram 5] 10 is a cross-sectional view showing a modified example of the valve portion 7 and the nozzle portion 21. FIG. [Figure 6] 2 is an enlarged cross-sectional view showing the vicinity of a valve seat surface seat portion 15b and a valve disc seat portion 17d of the valve seat member 15 in an enlarged manner. FIG. [Figure 7] FIG. 13 is a diagram showing a simulation result of the fuel flow velocity in the case where a tapered surface 15c is not provided. [Figure 8] FIG. 13 is a diagram showing a simulation result of the fuel flow velocity when a cone-shaped tapered surface 15c is provided. [Figure 9] FIG. 13 is a diagram showing a simulation result of the fuel flow velocity in the case where the tapered surface 15c is provided as a curved surface formed by a curve that is convex radially inward. [Figure 10] 1 is a cross-sectional view of an internal combustion engine 100 equipped with a fuel injection valve 1. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] An embodiment of the present invention will be described with reference to the drawings.

[0010] The overall configuration of a fuel injection valve 1 will be described with reference to Fig. 1. Fig. 1 is a cross-sectional view showing a cross section along a valve axis (central axis) 1a of a fuel injection valve 1 according to the present invention.

[0011] The central axis 1a of the fuel injection valve 1 coincides with the axis (valve axis) of a mover 27 with which a valve element 17 (described later) is integrally provided, and coincides with the central axis of a cylindrical body 5 (described later). The central axis 1a also coincides with the center line of a valve seat surface (conical surface) 15b (described later).

[0012] The fuel injection valve 1 is provided with a cylindrical body 5 made of a metal material that extends from an upper end to a lower end. A fuel flow passage 3 is configured inside the cylindrical body 5 so as to extend substantially along a central axis 1a. In FIG. 1, the upper end is called the base end, and the lower end is called the tip end. The names of the base end and the tip end are based on the direction of fuel flow. That is, in the direction of fuel flow, the base end is on the upstream side, and the tip end is on the downstream side. The vertical relationship described in this specification is defined based on FIG. 1, and does not necessarily coincide with the vertical direction when the fuel injection valve 1 is installed in an internal combustion engine.

[0013] A fuel supply port 2 is provided at the base end of the cylindrical body 5. A fuel filter 13 is attached to this fuel supply port 2. The fuel filter 13 is a member for removing foreign matter mixed in the fuel. In addition, an O-ring 11 is disposed at the base end of the cylindrical body 5. The O-ring 11 functions as a sealant when the fuel injection valve 1 is connected to a fuel pipe.

[0014] The valve portion 7 is formed at the tip of the cylindrical body 5 and is composed of a valve element 17 and a valve seat member 15 , and the valve seat member 15 is fixed to the inside of the tip side of the cylindrical body 5 .

[0015] A driving unit 9 for driving the valve body 17 is disposed in the middle of the cylindrical body 5. The driving unit 9 is composed of an electromagnetic actuator. Specifically, the driving unit 9 is composed of a fixed core 25, a movable element (movable member) 27, an electromagnetic coil 29, and a yoke 33.

[0016] The fixed core 25 is made of a magnetic metal material and is fixed by press fitting or the like to the inside of the longitudinal middle part of the cylindrical body 5. The fixed core 25 is formed in a cylindrical shape and has a through hole 25a that passes through the center in the direction along the central axis 1a.

[0017] The movable element 27 is disposed inside the cylindrical body 5 on the tip side of the fixed core 25. A movable core 27a is provided on the base end side of the movable element 27. The movable core 27a faces the fixed core 25 via a minute gap δ. A small diameter portion (rod portion) 27b is formed on the tip side of the movable element 27, and the valve element 17 is fixed to the tip of the small diameter portion 27b by welding. The small diameter portion 27b constitutes a connection portion that connects the movable core 27a and the valve element 17.

[0018] The movable element 27 displaces the valve element 17 in the valve opening / closing direction. The valve element 17 of the movable element 27 is in sliding contact with the guide surface 15a1 of the valve seat member 15, and the outer peripheral surface of the movable core 27a is in sliding contact with the inner peripheral surface of the cylindrical body 5. As a result, the movement of the movable element 27 in the direction along the central axis 1a (valve opening / closing direction) is guided at two points separated in the valve axis direction (direction along the central axis 1a).

[0019] The electromagnetic coil 29 is disposed on the outer periphery of the cylindrical body 5, and is electrically connected to a connector pin 43 provided on the connector 41 via a wiring member 45. A drive circuit (not shown) is connected to the connector 41, and a drive current is applied to the electromagnetic coil 29 via the connector pin 43 and the wiring member 45.

[0020] The yoke 33 is made of a magnetic metal material, is disposed so as to cover the outer periphery of the electromagnetic coil 29, and also serves as a housing for the fuel injection valve 1. The yoke 33, together with the movable core 27a and the fixed core 25, constitutes a magnetic path for magnetic flux generated by energizing the electromagnetic coil 29.

[0021] A coil spring 39 is disposed in a compressed state between an adjuster 35 fixed in the through hole 25a of the fixed core 25 and the movable core 27a. The coil spring 39 functions as a biasing member that biases the movable element 27 in a direction in which the valve body 17 abuts against the valve seat surface 15b (valve closing direction). By adjusting the position of the adjuster 35 in the direction along the central axis 1a, the biasing force of the coil spring 39 on the movable element 27 (i.e., the valve body 17) is adjusted.

[0022] An O-ring 46 is fitted onto the tip end of the cylindrical body 5. The O-ring 46 functions as a seal to ensure liquid-tightness and air-tightness between the inner peripheral surface of an insertion port 109a (see FIG. 8) formed on the internal combustion engine side and the outer peripheral surface of the yoke 33 when the fuel injection valve 1 is attached to the internal combustion engine.

[0023] A resin cover 47 is molded from the middle portion of the fuel injection valve 1 to the vicinity of the base end portion. The resin cover 47 covers the wiring member 45, and the connector 41 is integrally formed with the resin cover 47.

[0024] Next, the operation of the fuel injection valve 1 will be described.

[0025] When the electromagnetic coil 29 is not energized (i.e., no driving current flows), the movable element 27 is biased in the valve closing direction by the coil spring 39, and the valve element 17 is in contact (seated) with the valve seat surface 15b. In this case, a gap δ exists between the tip end face of the fixed core 25 and the base end face of the movable core 27a. In this embodiment, the gap δ is equal to the stroke of the movable element 27 (i.e., the valve element 17) when the valve is open.

[0026] When the electromagnetic coil 29 is energized and a driving current flows, a magnetic flux is generated in a magnetic path formed by the movable core 27a, the fixed core 25, and the yoke 33. This magnetic flux generates a magnetic attraction force between the fixed core 25 and the movable core 27a, which face each other across the gap δ. When this magnetic attraction force overcomes the resultant force of the coil spring 39 and the fuel pressure acting on the movable core 27 in the valve closing direction, the movable core 27 starts to move in the valve opening direction. When the valve body 17 moves away from the valve seat surface 15b, a gap (fuel flow path) is formed between the valve body 17 and the valve seat surface 15b, and fuel injection begins. In this embodiment, when the movable core 27 moves in the valve opening direction by a distance δ equal to the gap δ and the movable core 27a abuts against the fixed core 25, the movable core 27a stops moving in the valve opening direction and opens and reaches a stationary state.

[0027] When the power supply to the electromagnetic coil 29 is cut off, the magnetic attractive force decreases and eventually disappears. When the magnetic attractive force decreases and becomes smaller than the biasing force of the coil spring 39, the movable element 27 starts to move in the valve closing direction. When the valve element 17 abuts against the valve seat surface 15b, the valve element 17 closes the valve portion 7 and comes to a stationary state.

[0028] Next, the structures of the valve portion 7 and the fuel injection portion 21 will be described in detail with reference to Figs. 2 and 3. Fig. 2 is an enlarged longitudinal section (corresponding to the section along the arrows II-II in Fig. 3) of the valve portion 7 and the vicinity of the fuel injection portion 21 (nozzle portion) of the fuel injection valve 1 shown in Fig. 1. Fig. 3 is a plan view of the nozzle plate 21n as viewed from the direction of the arrows III-III in Fig. 1. The plan view of Fig. 3 is a plan view of the nozzle plate 21n as viewed from the inlet side of the fuel injection hole, and is a plan view of the upper end surface 21nu side of the nozzle plate 21n. The upper end surface 21nu is a surface facing the tip surface (downstream end surface) 15t of the valve seat member 15. The end surface of the nozzle plate 21n opposite to the upper end surface 21nu is called the lower end surface 21nb.

[0029] In this embodiment, the nozzle portion (fuel injection portion) 21 is composed of a valve seat member 15 and a nozzle plate 21n. That is, the valve seat member 15 constitutes a first nozzle member constituting the nozzle portion 21, and the nozzle plate 21n constitutes a second nozzle member constituting the nozzle portion 21. The nozzle hole plate 21n, in which the fuel injection holes 220, the lateral passages 211 and the swirl chamber 212 are formed, is joined to a tip end surface 15t on the nozzle portion main body side constituted by the valve seat member 15.

[0030] As shown in FIG. 2, the nozzle plate 21n is made of a plate-like member having flat end faces, and the upper end face 21nu and the lower end face 21nb are parallel to each other. That is, the nozzle plate 21n is made of a flat plate having a uniform thickness. The nozzle plate 21n is fixed to the valve seat member 15 by laser welding 23. The laser welded portion 23 goes around the injection hole forming region in which the fuel injection hole 220 is formed so as to surround the injection hole forming region. The valve seat member 15 may be pressed into the inner side of the tip end side of the cylindrical body 5 and then fixed to the cylindrical body 5 by laser welding. In this embodiment, the fuel injection valve 1 is configured so that the central axis 1a intersects with the nozzle plate 21n at the center 21no.

[0031] The downstream end surface 15t of the valve seat member 15 is configured as a flat surface perpendicular to the central axis 1a. The nozzle plate 21n is fixed to the downstream end surface 15t of the valve seat member 15, and the downstream end surface 15t abuts against the upper end surface 21nu of the nozzle plate 21n.

[0032] The valve seat member 15 is inserted into the inside of the tip side of the cylindrical body 5 and fixed to the cylindrical body 5 by laser welding or the like. A nozzle plate 21n is attached to a downstream end face 15t of the valve seat member 15. The nozzle plate 21n is fixed to the valve seat member 15 so as to cover the opening of the valve seat member 15 formed by the valve body accommodating hole 15a (the opening of the fuel supply hole 15a3).

[0033] The valve seat member 15 is formed with a stepped valve body accommodating hole 15a that accommodates the valve body 17. The valve body accommodating hole 15a penetrates the valve seat member 15 in a direction along the central axis 1a, and the downstream end of the valve body accommodating hole 15a opens into a downstream end face 15t of the valve seat member 15.

[0034] A guide surface 15a1 is formed in the valve body accommodating hole 15a. The guide surface 15a1 guides the movement of the valve body 17 in a direction along the central axis 1a. In this embodiment, the valve body 17 is configured as a spherical ball valve. For this reason, a portion of the valve body 17 facing the guide surface 15a1 is provided with a plurality of cutout surfaces 17a spaced apart in the circumferential direction. The cutout surfaces 17a form gaps between themselves and the inner peripheral surface (guide surface) 15a1 of the valve seat member 15. This gap forms a fuel passage. It is possible to configure the valve body 17 with a valve other than a ball valve. For example, a needle valve may be used.

[0035] The valve body accommodating hole 15a has a conical surface (frustum surface) 15a2 downstream of the guide surface 15a1. The conical surface 15a2 is shaped so that its diameter decreases toward the downstream side, and constitutes a valve seat surface. That is, the valve seat surface 15a2 is formed on the valve seat member 15. The valve seat surface 15a2 and the valve body 17 cooperate to open and close the fuel passage. When the valve body 17 comes into contact with the valve seat surface 15a2, the fuel passage is closed, and when the valve body 17 moves away from the valve seat surface 15a2, the fuel passage is opened.

[0036] A portion (position) 15b of the valve seat surface 15a2 where the valve element 17 abuts is called a valve seat surface seat portion or valve seat surface seat position, and a portion (position) 17d of the valve element 17 where the valve seat surface 15a2 abuts is called a valve element seat portion or valve element seat position.

[0037] A fuel introduction hole (fuel supply hole) 15a3 and a reverse tapered surface 15c are provided at the downstream end of the valve body accommodating hole 15a. The fuel introduction hole 15a3 is provided on the downstream end side of the valve seat surface 15a2 and is connected to the downstream end of the valve seat surface 15a2. The downstream end of the fuel introduction hole 15a3 opens to the downstream end face 15t of the valve seat member 15 and constitutes a fuel passage that introduces fuel into the swirl passage 210.

[0038] The reverse tapered surface 15c is provided on the downstream end side of the fuel introduction hole 15a3 and is connected to the downstream end of the fuel introduction hole 15a3. The reverse tapered surface 15c is shaped so that the diameter increases toward the downstream side. The reverse tapered surface 15c will be described in detail later.

[0039] As shown in Fig. 3, the nozzle plate 21n is formed with lateral passages 211-1, 211-2, 211-3, 211-4, swirl chambers 212-1, 212-2, 212-3, 212-4, and fuel injection holes 220-1, 220-2, 220-3, 220-4. The four sets of swirl passages 210-1, 210-2, 210-3, 210-4 and fuel injection holes 220-1, 220-2, 220-3, 220-4 are configured similarly, so they will not be distinguished from each other and will be described as the lateral passage 211, the swirl chamber 212, and the fuel injection hole 220. If the configuration of each set is changed, it will be described as appropriate. The lateral passage 211 and the swirl chamber 212 constitute a swirl passage 210 for applying a swirling force to the fuel and injecting the swirled fuel from the fuel injection hole 220 .

[0040] In order to receive fuel from the fuel inlet hole 15a3, the upstream ends of the lateral passages 211 of the swirl passage 210 are provided facing the opening surface of the fuel inlet hole 15a3. In this embodiment, as shown in Fig. 3, the upstream ends of the four sets of lateral passages 211-1, 211-2, 211-3, 211-4 are connected to each other, but each of the lateral passages 211-1, 211-2, 211-3, 211-4 may be an independent fuel passage.

[0041] 2, the lateral passages 211, the swirl chamber 212, and the fuel injection holes 220 are all formed in the nozzle plate 21n, which is made up of a single plate-like member. The nozzle plate 21n can be made up of multiple plates, for example, by dividing it in the thickness direction. For example, the lateral passages 211 and the swirl chamber 212 are formed in one plate, and the fuel injection holes 220 are formed in another plate. These two plates may then be stacked to form the nozzle plate 21n.

[0042] 2, the fuel injection holes 220 are formed parallel to the central axis 1a, but may be inclined at an angle greater than 0° with respect to the central axis 1a. The fuel injection holes 220 may be inclined in different directions to inject fuel in a plurality of directions.

[0043] 3, in this embodiment, the swirl passage 210-1 and the fuel injection hole 220-1 form one fuel passage, the swirl passage 210-2 and the fuel injection hole 220-2 form one fuel passage, the swirl passage 210-3 and the fuel injection hole 220-3 form one fuel passage, and the swirl passage 210-4 and the fuel injection hole 220-4 form one fuel passage. The swirl passage 210-1 is composed of the lateral passage 211-1 and the swirl chamber 212-1, the swirl passage 210-2 is composed of the lateral passage 211-2 and the swirl chamber 212-2, the swirl passage 210-3 is composed of the lateral passage 211-3 and the swirl chamber 212-3, and the swirl passage 210-4 is composed of the lateral passage 211-4 and the swirl chamber 212-4.

[0044] In this embodiment, the nozzle plate 21n is configured with a total of four fuel passages, each consisting of a swirl passage 210 and a fuel injection hole 220. The four fuel passages are each formed radially from the center 21no of the nozzle plate 21n toward the outer periphery. That is, the lateral passages 211 are provided radially from the center 21no of the nozzle plate 21n toward the outer periphery, and extend in the radial direction of the nozzle plate 21n. The fuel passages are also formed at angular intervals of 90° in the circumferential direction.

[0045] The number of sets of the swirl passage 210 and the fuel injection holes 220 is not limited to four, but may be two, three, or five or more. Alternatively, there may be only one set of the swirl passage 210 and the fuel injection holes 220. In this embodiment, the lateral passage 211 is formed in a straight line, but the lateral passage 211 may be curved or bent.

[0046] The lateral passage 211 is provided downstream of the valve seat surface 15a2 and constitutes a radial fuel passage that flows fuel radially outward. The lateral passage 211 supplies the fuel introduced from the fuel introduction hole 15a3 to the fuel injection hole 220. The fuel introduction hole 15a3 is provided downstream of the valve seat surface 15a2 and upstream of the lateral passage (radial fuel passage) 211, and causes the fuel that has flowed down the valve seat surface 15a2 to flow in the axial direction and introduce it into the lateral passage (radial fuel passage) 211. Here, the axial direction is a direction along the central axis 1a and coincides with the central axis of the cone shape formed by the valve seat surface 15a2. The radial direction is a direction perpendicular to the central axis of the valve seat surface 15a2 and coincides with the radial direction of the bottom surface of the cone shape formed by the valve seat surface 15a2.

[0047] Here, the relationship between the swirl chamber 212 and the fuel injection hole 220 will be described in detail with reference to Fig. 4. Fig. 4 is an enlarged plan view showing the swirl chamber 212 and the fuel injection hole 220 (an enlarged plan view of part IV shown in Fig. 3).

[0048] The lateral passage 211 is connected to the swirl chamber 212 so as to be offset from the center O1 of the swirl chamber 212 of the fuel injection hole 220. The downstream end of the lateral passage 211 is connected to an inner circumferential wall (side wall) 212c of the swirl chamber 212 and forms an opening in the inner circumferential wall 212c. The inner circumferential wall 212c of the swirl chamber 212 is formed to form a circle around the inlet opening of the fuel injection hole 220 so as to swirl the fuel that has flowed into the swirl chamber 212 from the lateral passage 211. That is, a swirl flow passage for fuel with 212b as a bottom surface is formed between the inner circumferential wall 212c of the swirl chamber 212 and the inlet opening of the fuel injection hole 220.

[0049] In this embodiment, the swirl chamber 212 and the inlet opening of the fuel injection hole 220 are arranged so that the center O1 of the swirl chamber 212 and the center O2 of the inlet opening (the center of the inlet opening edge 220i) are different. However, the swirl chamber 212 and the inlet opening of the fuel injection hole 220 may be arranged so that the center O1 of the swirl chamber 212 and the center O2 of the inlet opening coincide with each other.

[0050] The lateral passage 211 has a rectangular cross section perpendicular to the extension direction (fuel flow direction), and side walls (side surfaces) 211o, 211i and a bottom surface 211b are formed by the nozzle plate 21n. An upper surface (ceiling surface) 211e (see FIG. 2) of the lateral passage 211 is formed by the downstream end surface 15t of the valve seat member 15.

[0051] A downstream end of the side wall 211o of the lateral passage 211 is connected to a starting end 212cs of the inner circumferential wall 212c of the swirl chamber 212. A downstream end of the side wall 211i of the lateral passage 211 is connected to a terminal end 212ce of the inner circumferential wall 212c of the swirl chamber 212. That is, the side wall 211o is connected to the upstream end of the inner circumferential wall 212c in the flow direction of the swirling fuel, and the side wall 211i is connected to the downstream end of the inner circumferential wall 212c, and the downstream end of the lateral passage 211 opens to the inner circumferential wall 212c.

[0052] The start end 212cs is an end of the swirl chamber 212 located on the side where the fuel flows in (upstream side), and is an end located on the upstream side in the swirling direction of the fuel. On the other hand, the end end 212ce is an end located on the downstream side in the swirling direction of the fuel.

[0053] In this embodiment, the swirl chamber 212 is formed such that the inner circumferential wall 212c between the starting end 212cs and the terminal end 212ce has a constant radius R from the center O1. That is, the inner circumferential wall 212c is formed of a part of a circumference that forms a perfect circle or a perfect circle. As a result, a bottom surface 212b that constitutes a fuel passage is formed between the inlet opening edge 220i of the fuel injection hole 220 and the inner circumferential wall 212c of the swirl chamber 212.

[0054] The inner circumferential wall 212c may be formed to describe a spiral curve or an involute curve so as to swirl the fuel while approaching the inlet opening or the center O1 of the fuel injection hole 220. In this case, the cross-sectional area of ​​the swirl flow passage gradually decreases toward the downstream side. When the inner circumferential wall 212c forms a spiral curve, the center O1 of the swirl chamber becomes the swirl center of the spiral curve. When the inner circumferential wall 212c forms an involute curve, the center O1 of the swirl chamber becomes the center of the base circle.

[0055] A part of the inlet opening edge 220i of the fuel injection hole 220 is disposed on the side wall 211o side or on the side of the extension line 211ol of the side wall 211o beyond the extension line 211il of the side wall 211i connected to the terminal end portion 212ce. That is, a part of the inlet opening of the fuel injection hole 220 is disposed on the side wall 211o side or on the side of the extension line 211ol of the side wall 211o beyond the extension line 211il of the side wall 211i. Therefore, in the fuel injection valve 1 of this embodiment, the extension line 211il211il and the inlet opening edge 220i of the fuel injection hole 220 intersect at two points 212ia, 212ib.

[0056] Here, the extension line 211il is an imaginary line that is in contact with the side wall 211i and extends along the side wall 211i. Moreover, the extension line 211ol is an imaginary line that is in contact with the side wall 211o and extends along the side wall 211o.

[0057] Next, the fuel flow in the swirl passage 210 and the fuel injection hole 220 will be described with reference to FIG.

[0058] A portion of the fuel that has flowed from the lateral passage 211 into the swirl chamber 212 flows along the inner circumferential wall 212c of the swirl chamber 212 as indicated by arrow F1, and swirls around the inlet opening of the fuel injection hole 220. At this stage, a swirling force is imparted to the fuel. The fuel flow to which the swirling force has been imparted flows into the fuel injection hole 220 while swirling. The fuel injected from the fuel injection hole 220 forms a liquid film while maintaining the swirling force, and breaks up into droplets while further swirling. This forms an atomized fuel spray.

[0059] In this embodiment, the inlet opening (inlet opening edge 220i) of the fuel injection hole 220 is configured to extend beyond the extension line 211il of the side wall 211i toward the side wall 211o, so that a part of the fuel flowing from the lateral passage 211 into the swirl chamber 212 flows into the fuel injection hole 220 without making much of a turn in the swirl chamber 212, as shown by the arrow F2. By changing the amount of the fuel flowing into the fuel injection hole 220 that extends toward the side wall 211o at the inlet opening, it is possible to adjust the ease with which the fuel flows into the fuel injection hole 220. Usually, the greater the amount of the fuel flowing into the side wall 211o at the inlet opening of the fuel injection hole 220, the greater the flow rate of the fuel flowing into the fuel injection hole 220.

[0060] The fuel injection valve 1 may not necessarily have a swirl passage 210 upstream of the fuel injection hole 220. An embodiment of the fuel injection valve 1 not having the swirl passage 210 will be described with reference to Fig. 5. Fig. 5 is a cross-sectional view showing a modified example of the valve portion 7 and the nozzle portion 21.

[0061] A protruding portion 21na is formed in the center of the nozzle plate 21n so as to protrude outward. The protruding portion 21na is formed with a curved surface (for example, a spherical surface). A fuel chamber 21a is formed inside the protruding portion 21na. This fuel chamber 21a is connected to a fuel introduction hole 15a3 formed in the valve seat member 15, and fuel is supplied to the fuel chamber 21a through the fuel introduction hole 15a3. That is, the fuel chamber 21a is provided on the downstream side of the valve seat surface 15a2, and constitutes a radial fuel passage that flows fuel radially outward. The fuel chamber 21a supplies the fuel introduced from the fuel introduction hole 15a3 to the fuel injection hole 220.

[0062] The protruding portion 21na is formed with a plurality of fuel injection holes 220. The fuel injection holes 220 are provided so that their inlet opening faces are positioned outside the opening position of the fuel introduction hole 15a3 in the radial direction centered on the central axis (valve axis) 1a. That is, in this embodiment, the nozzle plate 21n has the protruding portion 21na that forms the fuel chamber 21a between itself and the downstream end face 15t of the valve seat member 15, and the fuel injection holes 220 are formed in the protruding portion 21na so as to be positioned outside the fuel introduction hole 15a3 in the radial direction.

[0063] The central axis 220a of the fuel injection hole 220 may be parallel to the central axis (valve axis) 1a or may be inclined. Also, the protruding portion 21na may not be provided, and the configuration may be such that the swirl chamber 212 is removed from the swirl passage 210 in the configurations shown in Figures 2 and 3, for example.

[0064] 2 and 5 show an example in which the nozzle plate 21n is configured from a single plate-like member, but it may be configured from a plurality of plates, for example, by dividing it in the thickness direction.

[0065] Next, the reverse tapered surface 15c formed on the valve seat member 15 will be described in detail with reference to Fig. 6. Fig. 6 is an enlarged cross-sectional view showing the vicinity of the valve seat surface seat portion 15b and the valve body seat portion 17d of the valve seat member 15. In the embodiment according to the present invention, various forms can be adopted for the fuel injection hole 220. Fig. 6 focuses on the vicinity of the valve seat member 15 and the valve body 17.

[0066] The downstream end of the valve body receiving hole 15a of the valve seat member 15 is provided with a reverse tapered surface 15c following the fuel introduction hole 15a3. That is, the reverse tapered surface 15c is provided on the downstream end side of the fuel introduction hole 15a3 and is connected to the downstream end of the fuel introduction hole 15a3. The tapered surface 15c has a shape that expands in diameter toward the downstream side. The reverse tapered surface 15c constitutes a connection surface that connects the downstream end 15a30 of the fuel introduction hole 15a3 and the inner peripheral portion (inner peripheral edge) 15t1 of the downstream end face 15t of the valve seat member 15. Here, the inner peripheral portion (inner peripheral edge) 15t1 of the downstream end face 15t becomes the outer peripheral edge of the reverse tapered surface 15c.

[0067] The reverse tapered surface 15c in this embodiment is formed in a conical shape. However, the reverse tapered surface 15c is not limited to a conical shape, and may be a shape other than a conical shape as long as the shape expands toward the downstream side. For example, when viewed in the cross section of FIG. 4, the reverse tapered surface 15c may be configured as a curved surface having a curve that is convex toward the inside in the radial direction. In this way, the reverse tapered surface 15c is not limited to a conical shape, and may be called an expanding portion (expanding surface) because the diameter expands toward the downstream side.

[0068] The expanded diameter portion 15c is provided downstream of the fuel introduction hole 15a3 and expands in diameter toward the downstream side. The expanded diameter portion 15c is provided such that a downstream end 15c2 forms an opening in a downstream end face 15t of the valve seat member 15, and an upstream end 15c1 is connected to a downstream end 15a30 of the fuel introduction hole 15a3. Although the expanded diameter portion 15c is treated as being separate from the fuel introduction hole 15a3, it may be considered as being part of the fuel introduction hole 15a3.

[0069] Although it is common to chamfer the corners where two surfaces meet in a workpiece, it is difficult to expect such chamfering to have an effect of suppressing flow separation. In this embodiment, in order to obtain the effect of suppressing flow separation, it is preferable that the axial dimension L15c of the reverse tapered surface 15c is 1 / 4 or more and 1 / 2 or less of the axial dimension L1, which is the sum of the axial dimension L15a3 of the fuel introduction hole 15a3 and the axial dimension L15c of the reverse tapered surface 15c. Moreover, it is preferable that the radial dimension D15c of the reverse tapered surface 15c is set to a size that is 3 / 4 or more of the axial dimension L15c and that the reverse tapered surface 15c does not overlap in the radial direction with the inlet opening surface of the fuel injection hole 220. In Fig. 6, the inlet opening surface of the fuel injection hole 220 is outside the range on the right side of the paper, and the reverse tapered surface 15c does not overlap in the radial direction with the inlet opening surface of the fuel injection hole 220. This means that the outer peripheral edge 15t1 of the reverse tapered surface 15c is located radially inward of the portion 220ic located in the inlet opening edge 220i of the fuel injection hole 220 that is located in the radially innermost position (the side of the center 21no of the nozzle plate 21n).

[0070] If the size of the reverse tapered surface 15c is made too large, the effect of reducing the thickness of the fuel film LF at the outlet of the fuel injection hole 220 cannot be obtained, as will be described later.

[0071] The effect of the inverse tapered surface 15c will be described with reference to FIGS. Fig. 7 is a diagram showing the simulation results of the fuel flow velocity when the reverse tapered surface 15c is not provided. In Fig. 7, (a) shows the simulation results of the fuel flow velocity in the lateral passage 211, (b) shows the simulation results of the fuel flow velocity in the fuel injection hole 220, (c) shows the simulation results of the fuel flow velocity on the upper surface of the lateral passage 211, and (d) shows the simulation results of the fuel flow velocity at the outlet of the fuel injection hole 220.

[0072] If the reverse tapered surface 15c is not provided, the downstream end of the fuel inlet hole 15a3 and the inner periphery (inner peripheral edge) of the downstream end face 15t of the valve seat member 15 are directly connected, and a corner where two faces perpendicularly intersect is formed at the connection portion between the fuel inlet hole 15a3 and the downstream end face 15t of the valve seat member 15. The fuel flow flowing in the axial direction (direction along the central axis 1a) through the fuel inlet hole 15a3 is strong, and the fuel flow that flows into the lateral passage 211 and changes direction to the radial direction flows in a manner that separates from the downstream end face 15t of the valve seat member 15, causing energy loss.

[0073] It can be seen that the separation portion SF appears in (a), and in (b) that the thickness of the fuel liquid film LF in the fuel injection hole 220 becomes thicker on the deep side of the lateral passage 211.

[0074] 13(c) is a graph in which the fuel flow velocity at the upper surface of the lateral passage 211 in FIG. 13(a) is plotted with the position D1 on the horizontal axis and the flow velocity on the vertical axis. In FIG. 13(c), it can be seen that a drop in the fuel flow velocity occurs due to the separation portion SF when D1 is in the range of 0.5 to 1.0.

[0075] 10(d) is a graph in which the fuel flow velocity at the exit of the fuel injection hole 220 in FIG. 10(b) is plotted with position D2 on the horizontal axis and flow velocity on the vertical axis. In FIG. 10(d), the phenomenon seen in FIG. 10(b) in which the thickness of the fuel liquid film LF becomes larger at the back side of the lateral passage 211 can be seen.

[0076] Fig. 8 is a diagram showing the simulation results of the fuel flow velocity when the conical reverse tapered surface 15c is provided. In Fig. 8, (a) shows the simulation results of the fuel flow velocity in the lateral passage 211, (b) shows the simulation results of the fuel flow velocity in the fuel injection hole 220, (c) shows the simulation results of the fuel flow velocity on the upper surface of the lateral passage 211, and (d) shows the simulation results of the fuel flow velocity at the outlet of the fuel injection hole 220.

[0077] In Fig. 8, a conical surface similar to that shown in Fig. 6 is provided as the inverse tapered surface 15c, and the size of the conical surface is varied as a parameter. Fig. 8(a) shows that the inverse tapered surface 15c suppresses the generation of the separation portion SF. The suppression of the generation of the separation portion SF can also be seen from the suppression of the decrease in the fuel flow velocity in Fig. 8(c).

[0078] From (d), it can be seen that the flow velocity at the outlet of the fuel injection hole 220 increases, and that the thickness of the fuel liquid film LF can be reduced at the back side of the lateral passage 211 by optimizing the size of the reverse tapered surface 15c. This makes it possible to achieve atomization of the fuel spray, a wider angle, and lower penetration. On the other hand, if the reverse tapered surface 15c is made too large, the thickness of the liquid film LF becomes the same as when the reverse tapered surface 15c is not provided. However, even in this case, the effects of atomization of the fuel spray, a wider angle, and lower penetration can still be obtained.

[0079] 9 is a diagram showing the results of simulating the fuel flow velocity when the reverse tapered surface 15c is provided as a curved surface formed of a curve that is convex radially inward. In FIG. 9, (a) shows the simulation result of the fuel flow velocity in the lateral passage 211, (b) shows the simulation result of the fuel flow velocity in the fuel injection hole 220, (c) shows the simulation result of the fuel flow velocity on the upper surface of the lateral passage 211, and (d) shows the simulation result of the fuel flow velocity at the outlet of the fuel injection hole 220.

[0080] In Fig. 9, the inverse tapered surface 15c is a curved surface having a curve that is parallel to the central axis 1a of the cone shape formed by the valve seat surface 15a2 and that is convex toward the inside in the radial direction in a cross section including the central axis 1a. Fig. 9 shows the results of varying the size of the curved surface 15c as a parameter. Fig. 9(a) shows that the inverse tapered surface 15c suppresses the generation of the separation portion SF. The suppression of the generation of the separation portion SF can also be seen from the suppression of the decrease in the fuel flow velocity in Fig. 9(c).

[0081] From (d), it can be seen that the flow velocity at the exit of the fuel injection hole 220 increases, and the thickness of the fuel liquid film LF can be reduced at the back side of the lateral passage 211. This makes it possible to realize atomization of the fuel spray, a wider angle, and lower penetration.

[0082] Comparing the example of Fig. 8 with the example of Fig. 9, when the reverse tapered surface 15c is made too large in the case of Fig. 8, the thickness of the liquid film LF becomes the same as when the reverse tapered surface 15c is not provided, whereas such a tendency was not observed in the case of Fig. 9. From this, it is considered that the reverse tapered surface 15c formed of a curved surface that is convex toward the inside in the radial direction as shown in Fig. 9 is more preferable than the reverse tapered surface 15c formed of a conical surface as shown in Fig. 8 in terms of realizing atomization, widening of the angle, and low penetration of the fuel spray.

[0083] As described above, in this embodiment, by providing the reverse tapered surface 15c, it is possible to reduce the energy loss of the fuel flow toward the fuel injection hole 220 through the lateral passage 211. In this case, since the valve seat member 15 and the nozzle plate 21n are configured as separate members, it becomes easy to form the reverse tapered surface 15c from the downstream end face 15t side of the valve seat member 15 toward the back side of the fuel introduction hole 15a3, and the shape and size of the reverse tapered surface 15c can be freely processed. Depending on the shape of the reverse tapered surface 15c, the flow rate of the fuel flow can be changed on the upstream side of the fuel injection hole 220, and the flow rate of the fuel flowing into the fuel injection hole 220 can be adjusted. Therefore, the shape (spray angle, particle size, etc.) of the fuel spray injected from the fuel injection hole 220 can be adjusted.

[0084] Providing the reverse tapered surface 15c is particularly effective for a multi-swirl structure in which the height (axial dimension) of the fuel flow passage toward the fuel injection hole 220 is small. Also, by increasing the flow velocity of the fuel flow, it is possible to increase the swirling force of the fuel flow F1 (see FIG. 4) which swirls in the swirling chamber 212 and flows into the fuel injection hole 220. In this case, the swirling force can be increased without changing the amount of the fuel flow F2 (see FIG. 4) which flows into the fuel injection hole 220 without swirling in the swirling chamber 212, so that the effect on the spray angle can be suppressed and the fuel spray can be atomized.

[0085] An internal combustion engine equipped with a fuel injection valve according to the present invention will be described with reference to Fig. 10. Fig. 10 is a cross-sectional view of an internal combustion engine 100 equipped with a fuel injection valve 1.

[0086] An engine block 101 of an internal combustion engine 100 has a cylinder 102 formed therein, and an intake port 103 and an exhaust port 104 are provided at the top of the cylinder 102. An intake valve 105 for opening and closing the intake port 103 is provided at the intake port 103, and an exhaust valve 106 for opening and closing the exhaust port 104 is provided at the exhaust port 104. An intake pipe 108 is connected to an inlet end 107a of an intake flow passage 107 formed in the engine block 101 and communicating with the intake port 103.

[0087] A fuel pipe 110 is connected to a fuel supply port 2 of the fuel injection valve 1 (see FIG. 1).

[0088] An attachment portion 109 for the fuel injection valve 1 is formed in the intake pipe 108, and an insertion port 109a for inserting the fuel injection valve 1 is formed in the attachment portion 109. The insertion port 109a penetrates to the inner wall surface (intake flow path) of the intake pipe 108, and the fuel injected from the fuel injection valve 1 inserted into the insertion port 109a is injected into the intake flow path. In the case of two-way spray, the target is an internal combustion engine in which two intake ports 103 are provided in the engine block 101, and each fuel spray is injected toward each intake port 103 (intake valve 105).

[0089] The present invention is not limited to the above-described embodiments and modified examples, and it is possible to delete some of the configurations, add other configurations not described, or replace some of the configurations. [Explanation of symbols]

[0090] DESCRIPTION OF THE PREFERRED EMBODIMENTS 1...fuel injection valve, 1a...central axis of fuel injection valve 1 (central axis of valve seat surface 15a2), 15...valve seat member, 15a2...valve seat surface, 15a3...fuel introduction hole, 15a30...downstream end of fuel introduction hole 15a3, 15c...expanded portion (reverse tapered surface), 15c1...upstream end of expanded portion 15c, 15c2...downstream end of expanded portion 15c, 15t...downstream end face of valve seat member 15, 17...valve body, 21a...fuel chamber (radial fuel passage), 21n...nozzle plate, 21na...projection portion, 211...lateral passage (radial fuel passage), 212...swirl chamber, 220...fuel injection hole.

Claims

1. a valve seat surface to which the valve disc moves; a radial fuel passage provided downstream of the valve seat surface and configured to allow fuel to flow radially outward; a fuel introduction hole provided downstream of the valve seat surface and upstream of the radial fuel passage, for introducing fuel that has flowed down the valve seat surface into the radial fuel passage by causing the fuel to flow in an axial direction; a fuel injection hole provided downstream of the radial fuel passage; an expanded diameter portion provided at a downstream portion of the fuel introduction hole and expanding in diameter toward the downstream side; A fuel injection valve comprising:

2. 2. The fuel injection valve according to claim 1, The valve seat surface is formed on a valve seat member, The fuel injection hole is formed in a nozzle plate, The nozzle plate is fixed to a downstream end surface of the valve seat member, a downstream end of the expanded diameter portion being provided so as to form an opening in the downstream end face of the valve seat member, and an upstream end of the expanded diameter portion being connected to the downstream end of the fuel inlet hole.

3. 3. The fuel injection valve according to claim 2, The fuel injection valve, wherein the expanded diameter portion is formed of a conical tapered surface.

4. 3. The fuel injection valve according to claim 2, The valve seat surface has a conical shape, The expanded diameter portion is a curved surface having a curve that is parallel to a central axis of a cone shape formed by the valve seat surface and that is convex radially inward in a cross section including the central axis.

5. 3. The fuel injection valve according to claim 2, The nozzle plate is a fuel injection valve having a swirl chamber formed upstream of the fuel injection hole, and a lateral passage formed upstream of the swirl chamber.

6. 3. The fuel injection valve according to claim 2, the nozzle plate has a protrusion that forms a fuel chamber between itself and the downstream end surface of the valve seat member, The fuel injection valve is formed on the protruding portion so as to be positioned radially outward from the fuel introduction hole.

Images