Fuel injector and method for manufacturing a fuel injector

Abstract

To provide a fuel injection valve capable of reducing a dead volume formed on a downstream side of a valve part.SOLUTION: A fuel injection valve of the present invention comprises a valve body and a valve seat that work together to open and close a fuel passage, and a turning passage and a fuel injection hole 220 provided on the downstream side of the valve body and valve seat. The turning passage has a turning chamber 212 in which a fuel turning flow path is formed, and a lateral passage 211 connected to the upstream side of the turning chamber 212. The fuel injection hole 220 is formed such that an inlet opening 220i of the fuel injection hole 220 opens to a bottom surface 212d of the turning chamber 212, and formed in a shape that tapers from the inlet opening 220i side toward an outlet opening 220o side.SELECTED DRAWING: Figure 4

Description

Technical Field

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[0001] The present invention relates to a fuel injection valve that generates swirling fuel upstream of a fuel injection hole and injects the swirling fuel from the fuel injection hole, and a method for manufacturing the same.

Background Art

[0002] Patent Document 1 describes a fuel injection valve having a swirling passage, a swirling chamber, a fuel injection hole, and a recess (buffer) (see paragraph 0036). By providing the recess (buffer), this fuel injection valve makes the liquid film distribution of the fuel inside and at the outlet of the fuel injection hole symmetrical (see paragraphs 0066 and FIGS. 5 and 6). On the other hand, the fuel injection hole is formed with the same diameter from its inlet to its outlet (see FIGS. 4 and 5).

Prior Art Document

Patent Document

[0003]

Patent Document 1

[0008] According to the present invention, the fuel flow velocity inside the fuel injection port can be increased in a fuel injector. This promotes the splitting of the injected fuel and improves the atomization of the fuel spray. Furthermore, a suitable manufacturing method for this fuel injector can be provided. [Brief explanation of the drawing]

[0009] [Figure 1] This is a cross-sectional view showing a cross-section along the valve axis (central axis) 1a of the fuel injection valve 1 according to the present invention. [Figure 2] This is a cross-sectional view (viewed along the line II-II in Figure 3) showing an enlarged view of the valve portion 7 and the vicinity of the fuel injection portion 21 (nozzle portion) of the fuel injection valve 1 shown in Figure 1. [Figure 3] This is a plan view of the nozzle plate 21n as seen from the direction of arrow III in Figure 2. [Figure 4] This is a plan view showing an enlarged view of the lateral passage, swing chamber, and fuel injection port (an enlarged plan view of section IV shown in Figure 3). [Figure 5]It is a cross-sectional view showing a V-V arrow view cross-section of FIG. 4. [Figure 6] It is a schematic view showing a processing method of a portion of the V-V arrow view cross-section of FIG. 4. [Figure 7] It is a cross-sectional view of an internal combustion engine 100 equipped with a fuel injection valve 1.

Mode for Carrying Out the Invention

[0010] An embodiment of the present invention will be described with reference to the drawings.

[0011] Using FIG. 1, the overall configuration of the fuel injection valve 1 will be described. FIG. 1 is a cross-sectional view showing a cross-section along the valve axis (central axis) 1a of the fuel injection valve 1 according to the present invention.

[0012] The central axis 1a of the fuel injection valve 1 coincides with the axis (valve axis) of the mover 27 to which the valve body 17 is integrally provided, and coincides with the central axis of the cylindrical body 5 described later. Further, the central axis 1a also coincides with the center line of the valve seat 15b described later.

[0013] The fuel injection valve 1 is provided with a cylindrical body 5 made of a metal material extending from the upper end portion to the lower end portion. The fuel flow path 3 is configured inside the cylindrical body 5 so as to substantially follow the central axis 1a. In FIG. 1, the upper end portion will be referred to as the base end portion, and the lower end portion will be referred to as the tip end portion. The terms base end portion and tip end portion are based on the flow direction of the fuel. That is, in the flow direction of the fuel, the base end portion is on the upstream side, and the tip end portion is on the downstream side. Also, the vertical relationship described in this specification is based on FIG. 1 and does not necessarily coincide with the vertical direction in the state where the fuel injection valve 1 is mounted on the internal combustion engine.

[0014] A fuel supply port 2 is provided at the base end portion of the cylindrical body 5. A fuel filter 13 is attached to the fuel supply port 2. The fuel filter 13 is a member for removing foreign substances mixed in the fuel.

[0015] An O-ring 11 is provided 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 the fuel piping.

[0016] The tip of the cylindrical body 5 is configured with a valve section 7 consisting of a valve body 17 and a valve seat member 15 (valve seat 15b). The valve seat member 15 has a stepped valve body housing hole 15a for housing the valve body 17. A conical surface is formed in the middle of the valve body housing hole 15a, and the valve seat 15b is formed on this conical surface. On the upstream side (base end side) of the valve body housing hole 15a from the valve seat 15b, a guide surface 15c is formed to guide the movement of the valve body 17 in a direction along the central axis 1a.

[0017] The valve seat 15b and the valve body 17 work together to open and close the fuel passage. The fuel passage is closed when the valve body 17 comes into contact with the valve seat 15b. Conversely, the fuel passage is opened when the valve body 17 moves away from the valve seat 15b.

[0018] The valve seat member 15 is inserted into the inner side of the tip of the cylindrical body 5 and fixed to the cylindrical body 5 by laser welding 19. The laser welding 19 is performed from the outer circumference of the cylindrical body 5 all the way around. The valve body housing hole 15a penetrates the valve seat member 15 in a direction along the central axis 1a. A nozzle plate 21n is attached to the lower end surface (tip surface) of the valve seat member 15. The nozzle plate 21n closes the opening of the valve seat member 15 formed by the valve body housing hole 15a. The valve body housing hole 15a is in communication with the outside of the fuel injection valve 1 through a fuel injection hole 220 provided in the nozzle plate 21n.

[0019] In this embodiment, a fuel injection unit 21 that injects swirling fuel is configured by a valve seat member 15 and a nozzle plate 21n. The nozzle plate 21n is fixed to the valve seat member 15 by a laser welded portion 23. The laser welded portion 23 surrounds the injection hole forming region where the fuel injection hole 220 is formed, and encircles this injection hole forming region. The valve seat member 15 may be press-fitted into the inner side of the tip side of the cylindrical body 5 and then fixed to the cylindrical body 5 by laser welding.

[0020] In this embodiment, the valve body 17 is a ball valve with a spherical shape. Therefore, multiple notched surfaces 17a are provided at circumferential intervals on the portion of the valve body 17 facing the guide surface 15c. These notched surfaces 17a form a gap between them and the inner circumferential surface (guide surface) 15c of the plate seat member 15. This gap constitutes the fuel passage. It should be noted that the valve body 17 can be constructed using a valve other than a ball valve. For example, a needle valve may be used.

[0021] In this embodiment, the valve section 7, including the valve seat member 15 and the valve body 17, and the nozzle plate 21n constitute a nozzle section for injecting fuel. The nozzle plate 21n (see Figure 4), which has fuel injection holes 220 and a swivel passage 210 (lateral passage 211 and swivel chamber 212) formed therein, is joined to the tip surface of the nozzle section body side on which the valve section 7 is formed.

[0022] A drive unit 9 for driving the valve body 17 is located in the middle of the cylindrical body 5. The drive unit 9 is composed of an electromagnetic actuator. Specifically, the drive unit 9 is composed of a fixed iron core 25, a movable element (movable member) 27, an electromagnetic coil 29, and a yoke 33.

[0023] The fixed core 25 is made of a magnetic metal material and is fixed to the inside of the longitudinal middle portion of the cylindrical body 5 by press-fitting or the like. The fixed core 25 is formed in a cylindrical shape and has a through hole 25a that penetrates through its center in a direction along the central axis 1a.

[0024] The movable element 27 is positioned inside the cylindrical body 5, closer to the tip than the fixed core 25. A movable core 27a is provided at the base end of the movable element 27. The movable core 27a faces the fixed core 25 with a small gap δ between them. A small-diameter portion (rod portion) 27b is formed at the tip end of the movable element 27, and the valve body 17 is fixed to the tip of this small-diameter portion 27b by welding. The small-diameter portion 27b constitutes a connecting portion that connects the movable core 27a and the valve body 17.

[0025] The movable element 27 displaces the valve body 17 in the valve opening / closing direction (valve axis direction). The movable element 27 is positioned such that the valve body 17 contacts the guide surface 15c of the valve seat member 15, and the outer surface of the movable core 27a contacts the inner surface of the cylindrical body 5. As a result, the movable element 27 is guided at two points separated in the valve axis direction (direction along the central axis 1a) during movement along the central axis 1a (valve opening / closing direction).

[0026] The electromagnetic coil 29 is fitted onto the outer circumference of the cylindrical body 5 at a position where the fixed core 25 and the movable core 27a face each other with a small gap δ between them, and is electrically connected to the connector pins 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 supplied to the electromagnetic coil 29 via the connector pins 43 and the wiring member 45.

[0027] The yoke 33 is made of a magnetic metal material and is positioned to cover the outer circumference of the electromagnetic coil 29, also serving as the housing for the fuel injection valve 1. Together with the movable core 27a and the fixed core 25, the yoke 33 forms a magnetic path for the magnetic flux generated when the electromagnetic coil 29 is energized.

[0028] A coil spring 39 is positioned in a compressed state between an adjuster 35, which is fixed within a 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 the direction in which the valve body 17 contacts the valve seat 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 movable element 27 (i.e., the valve body 17) by the coil spring 39 is adjusted.

[0029] An O-ring 46 is fitted to the tip of the cylindrical body 5. The O-ring 46 functions as a seal to ensure liquid-tightness and airtightness between the inner surface of the insertion port 109a (see Figure 7) formed on the internal combustion engine side and the outer surface of the yoke 33 when the fuel injection valve 1 is installed on the internal combustion engine.

[0030] A resin cover 47 is molded onto the fuel injector 1 from the middle section to near the base end. The resin cover 47 covers the wiring member 45, and the connector 41 is integrally formed by the resin cover 47.

[0031] Next, the operation of the fuel injector 1 will be explained.

[0032] When the electromagnetic coil 29 is not energized (i.e., no drive current is flowing), the movable element 27 is biased in the closing direction by the coil spring 39, and the valve body 17 is in contact with (seaten) the valve seat 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 body 17) when the valve is open.

[0033] When the electromagnetic coil 29 is energized and a drive current flows, a magnetic flux is generated in the magnetic path formed by the movable core 27a, the fixed core 25, and the yoke 33. This magnetic flux generates a magnetic attractive force between the fixed core 25 and the movable core 27a, which are opposite each other across the gap δ. When this magnetic attractive force overcomes the resultant force of the biasing force from the coil spring 39 and the fuel pressure acting on the movable element 27 in the valve closing direction, the movable element 27 begins to move in the valve opening direction. When the valve body 17 separates from the valve seat 15b, a gap (fuel passage) is formed between the valve body 17 and the valve seat 15b, and fuel injection begins. In this embodiment, when the movable element 27 moves a distance δ equal to the gap δ in the valve opening direction and the movable core 27a comes into contact with the fixed core 25, the movable core 27a is stopped from moving in the valve opening direction and reaches an open, stationary state.

[0034] When the current to the electromagnetic coil 29 is cut off, the magnetic attractive force decreases and eventually disappears. When the magnetic attractive force decreases to a level smaller than the biasing force of the coil spring 39, the movable element 27 begins to move in the valve closing direction. When the valve body 17 comes into contact with the valve seat 15b, the valve body 17 closes the valve section 7 and comes to a stationary state.

[0035] Next, the structure of the valve section 7 and the fuel injection section 21 will be described in detail using Figures 2 and 3. Figure 2 is an enlarged cross-sectional view (cross-sectional view taken along arrow II-II in Figure 3) showing the vicinity (nozzle section) of the valve section 7 and the fuel injection section 21 of the fuel injection valve 1 in Figure 1. Figure 3 is a plan view of the nozzle plate 21n as seen from the direction of arrow III in Figure 2.

[0036] The plan view in Figure 3 is a plan view of the nozzle plate 21n as seen from the inlet side of the fuel injection hole, and is a plan view of the upper end surface 21nu of the nozzle plate 21n. The upper end surface 21nu is the surface facing the tip surface 15t of the valve seat member 15. The end surface opposite to the upper end surface 21nu is called the lower end surface 21nb. In this embodiment, the central axis (valve axis) 27l of the movable element 27 is shown to be perfectly aligned with the central axis 1a of the fuel injection valve 1.

[0037] In this embodiment, as shown in Figure 2, the nozzle plate 21n is made of a plate-like member with both end faces being flat, and the upper end face 21nu and the lower end face 21nb are parallel. That is, the nozzle plate 21n is made of a flat plate with a uniform thickness. In this embodiment, the fuel injection valve 1 is configured such that the central axis 1a intersects the nozzle plate 21n at the center 21no of the nozzle plate 21n.

[0038] The tip surface (lower end surface) 15t of the valve seat member 15 is a flat surface perpendicular to the central axis 1a. The nozzle plate 21n is joined to the tip surface 15t of the valve seat member 15, and the tip surface 15t is in contact with the upper end surface 21nu of the nozzle plate 21n.

[0039] As shown in Figure 3, the nozzle plate 21n has 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.

[0040] The lateral passages 211-1, 211-2, 211-3, 211-4 and the swirl chambers 212-1, 212-2, 212-3, 212-4 constitute swirl passages 210-1, 210-2, 210-3, 210-4 for imparting a swirl force to the fuel and injecting swirl fuel from the fuel injection port 220.

[0041] In this embodiment, as shown in Figure 3, the swivel passage 210-1 is composed of a lateral passage 211-1 and a swivel chamber 212-1, the swivel passage 210-2 is composed of a lateral passage 211-2 and a swivel chamber 212-2, the swivel passage 210-3 is composed of a lateral passage 211-3 and a swivel chamber 212-3, and the swivel passage 210-4 is composed of a lateral passage 211-4 and a swivel chamber 212-4. Furthermore, the swivel passage 210-1 and the fuel injection port 220-1 form one fuel passage, the swivel passage 210-2 and the fuel injection port 220-2 form one fuel passage, the swivel passage 210-3 and the fuel injection port 220-3 form one fuel passage, and the swivel passage 210-4 and the fuel injection port 220-4 form one fuel passage.

[0042] In this embodiment, the four sets of fuel passages, each consisting of a swivel passage and a fuel injection port, are all configured similarly. Therefore, they will not be distinguished and will be described as the swivel passage 210, the lateral passage 211, the swivel chamber 212, and the fuel injection port 220. If the configuration differs for each set, it will be explained as appropriate.

[0043] The number of swivel passages 210 and fuel injection holes 220 is not limited to four sets; there may be two or three sets, or five or more sets. Alternatively, there may be only one set of swivel passages 210 and fuel injection holes 220.

[0044] As shown in Figure 2, the valve seat member 15 has a conical (frustoconical) valve seat surface 15b that tapers towards the downstream side. The downstream end of the valve seat surface 15b is connected to the fuel inlet 300. The downstream end of the fuel inlet 300 opens to the tip surface 15t of the valve seat member 15. The fuel inlet 300 constitutes a fuel passage that introduces fuel into the swivel passage 210.

[0045] The swivel passage 210 is provided with the upstream end of the lateral passage 211 facing the opening surface of the fuel inlet 300 in order to receive fuel from the fuel inlet 300. In this embodiment, as shown in Figure 3, the four sets of lateral passages 211-1, 211-2, 211-3, and 211-4 are configured so that their upstream ends communicate at the center 21no of the nozzle plate 21n, but each of the lateral passages 211-1, 211-2, 211-3, and 211-4 may be configured independently.

[0046] In this embodiment, as shown in Figure 2, the nozzle plate 21n, which is made of a single plate-like member, has all of the lateral passage 211, the swivel chamber 212, and the fuel injection holes 220 formed on it. The nozzle plate 21n can be made of multiple plates, for example, by dividing it in the thickness direction. For example, the lateral passage 211 and the swivel chamber 212 may be formed on one plate, and the fuel injection holes 220 may be formed on another plate. These two plates may then be stacked to form the nozzle plate 21n.

[0047] Furthermore, in this embodiment, as shown in Figure 2, the fuel injection holes 220 are formed parallel to the central axis 1a, but they may be inclined with respect to the central axis 1a. By varying the inclination direction, fuel may be injected in multiple directions.

[0048] In this embodiment, the four sets of fuel passages are each formed radially outward from the center 21no side of the nozzle plate 21n. That is, the lateral passages 211 are provided radially from the center 21no side of the nozzle plate 21n toward the outer circumference and extend radially across the nozzle plate 21n. Furthermore, each fuel passage is formed at a 90° angle interval in the circumferential direction.

[0049] Here, with reference to Figure 4, the configuration of the swivel passage 210 and the fuel injection port 220 will be described in detail. Figure 4 is an enlarged plan view showing the lateral passage 211, the swivel chamber 212, and the fuel injection port 220 (an enlarged plan view of section IV shown in Figure 3).

[0050] In this embodiment, in the plan view of Figure 4 (a plan view perpendicular to the central axis 1a), the inner circumferential wall (side wall) 212c of the slewing chamber 212 is formed in a spiral shape such that the distance from the center of the slewing chamber 212 decreases from the upstream end to the downstream end. The upstream end of the inner circumferential wall 212c is at the position of the line segment connecting points 212cs1 and 212cs2, and the downstream end is at the position of the line segment connecting points 212ce1 and 212ce2. That is, the surface S1 enclosed by the four points 212cs1, 212cs2, 212ce1, and 212ce2 becomes the interface between the slewing chamber 212 and the lateral passage 211.

[0051] Furthermore, the spiral shape can be, for example, formed by connecting multiple arcs with different radii R, or by employing an involute curve. In addition, the inner circumferential wall 212c of the rotating chamber 212 is not limited to a spiral shape; it may also be formed to form an arc with a constant radius R.

[0052] The fuel injection port 220 opens into the bottom surface 212d of the swirling chamber 212. In this embodiment, the center of the inlet opening 220i of the fuel injection port 220 coincides with the center of the swirling chamber 212, so O1 is also the center of the inlet opening 220i. A swirling fuel passage is formed between the inner circumferential wall 212c of the swirling chamber 212 and the inlet opening 220i of the fuel injection port 220. That is, the swirling chamber 212 has a bottom surface 212d into which the inlet opening surface 220i of the fuel injection port 220 opens, and a spiral-shaped inner circumferential wall 212c provided around the bottom surface 212d, and a swirling fuel passage is formed around the inlet opening surface 220i. The bottom surface 212d of the swirling chamber 212 is composed of a plane parallel to the upper end surface 21nu of the nozzle plate 21n.

[0053] The center of the inlet opening 220i of the fuel injection port 220 does not need to coincide with the center O1 of the swivel chamber 212; the center of the inlet opening 220i of the fuel injection port 220 may be positioned away from the center O1 of the swivel chamber 212.

[0054] The lateral passage 211 is connected to the swing chamber 212 so as to be offset from the center O1 of the swing chamber 212. Therefore, the lateral passage 211 is also offset from the center of the inlet opening 220i of the fuel injection port 220. In other words, the center line 211a of the lateral passage 211 is offset from the center O1 of both the swing chamber 212 and the inlet opening 220i of the fuel injection port 220.

[0055] The width of the lateral passage 211 is formed to be constant from the upstream side to the downstream side (towards the slewing chamber 212). That is, the width of the lateral passage 211 is constant in the direction along the center line 211a. The bottom surface 211d of the lateral passage 211 is formed to form a single plane together with the bottom surface 212d of the slewing chamber 212. Therefore, the width W211d of the bottom surface 211d of the lateral passage 211 is formed to be constant from the upstream side to the downstream side (towards the slewing chamber 212).

[0056] However, the width of the lateral passage 211 may change in the direction along the center line 211a.

[0057] The lateral passage 211 has one side wall (side surface) 211b, the other side wall (side surface) 211c, and the bottom surface 211d made of nozzle plates 21n, and the top surface (ceiling surface) 211e (see Figure 2) of the lateral passage 211 is made of the lower end surface 15t of the valve seat member 15.

[0058] The width of the lateral passage 211 is the distance between one side wall 211b and the other side wall 211c. In this embodiment, however, one side wall 211b and the other side wall 211c are not perpendicular to the bottom surface 211d of the lateral passage 211, but are configured to form inclined surfaces with respect to a line perpendicular to the bottom surface 211d (for example, the central axis 1a). Therefore, the distance between one side wall 211b and the other side wall 211c increases as they move away from the bottom surface 211d in the vertical direction. In other words, the distance between the side walls 211b and 211c increases as they move from the bottom surface 211d toward the tip surface (lower end surface) 15t of the valve seat member 15.

[0059] When we consider an extension line (first extension line) 211ba of the boundary line between the bottom surface 211d and the side wall 211b of the lateral passage 211, and an extension line (second extension line) 211ca of the boundary line between the bottom surface 211d and the side wall 211c of the lateral passage 211, the extension line 211ca is located on the center O1 side of the inlet opening surface 220i of the fuel injection hole 220 relative to the extension line 211ba, and the inlet opening 220i of the fuel injection hole 220 is formed to extend beyond the extension line 211ca and protrude towards the extension line 211ba side (towards the upstream end of the inner circumferential wall 212c).

[0060] On the other hand, the outlet opening 220o of the fuel injection hole 220 is formed to be located on the opposite side of the extension line 211ba from the extension line 211ba with respect to the extension line 211ca. That is, the outlet opening 220o of the fuel injection hole 220 is formed to be located on the side of the extension line 211cb of the upper edge of the side wall 211b of the lateral passage 211 (the side of the downstream end of the inner circumferential wall 212c) with respect to the extension line 211ca. Furthermore, the outlet opening 220o of the fuel injection hole 220 is formed to extend beyond the extension line 211cb to the side of the extension line 211ca.

[0061] The inlet opening 220i of the fuel injection port 220 is formed to extend beyond the extension line 211ca to the side of the extension line 211ba. As a result, a portion of the fuel flowing down the lateral passage 211 flows directly into the fuel injection port 220 from the inlet opening 220i that extends beyond the extension line 211ca to the side of the extension line 211ba, without having to rotate through the swirling chamber 212.

[0062] In this embodiment, the outlet opening 220o of the fuel injection hole 220 is formed to be located on the side of extension line 211cb relative to extension line 211ca. This allows for adjustment to suppress the amount of overhang of the inlet opening 220i from extension line 211ca to extension line 211ba, thereby suppressing a decrease in the turning force applied to the fuel.

[0063] Furthermore, since the outlet opening 220o of the fuel injection port 220 is formed to extend beyond the extension line 211cb and onto the extension line 211ca, the outlet opening 220o can be positioned within the extended downstream range W211 of the lateral passage 211. This makes it possible to obtain the effect of fuel flowing directly into the fuel injection port 220 without rotating the swivel chamber 212.

[0064] Next, with reference to Figure 4 and Figure 5, the configuration of the swivel chamber 212 and the fuel injection port 220 will be described in detail. Figure 5 is a cross-sectional view taken along the VV line in Figure 4.

[0065] The inner circumferential wall 212c of the swivel chamber 212 is not perpendicular to the bottom surface 212d, but is formed as an inclined surface inclined with respect to a line perpendicular to the bottom surface 212d (for example, the central axis 1a). In this case, the inner circumferential wall 212c of the swivel chamber 212 is inclined such that the tip surface (lower end surface) 15t side of the valve seat member 15 is further away from the center (centerline) O1 of the swivel chamber 212 with respect to the bottom surface 212d side. That is, the inner circumferential wall 212c of the swivel chamber 212 is inclined so that as it moves away from the bottom surface 212d side in the vertical direction, it moves away from the inlet opening of the fuel injection hole. In Figure 5, the position of the tip surface 15t of the valve seat member 15 is approximately the same as the position of the upper end surface 21nu of the nozzle plate 21n.

[0066] The inclination at the upstream ends 212cs1 and 212cs2 of the inner circumferential wall 212c of the swivel chamber 212 coincides with the inclination of the side wall 211b of the lateral passage 211 described above, and the inclined surface constituting the inner circumferential wall 212c and the inclined surface of the side wall 211b form a continuous inclined surface. The downstream ends 212ce1 and 212ce2 of the inner circumferential wall 212c are connected to the side wall 211c of the lateral passage 211 via a connecting part 211f, as shown in Figure 4. In this embodiment, the inclination angle of the inner circumferential wall 212c (angle of inclination with respect to a line perpendicular to the bottom surface 212d) is constant from the upstream ends 212cs1 and 212cs2 to the downstream ends 212ce1 and 212ce2, but it may be varied.

[0067] As described above, the swivel chamber 212 is formed such that the area of ​​the cross-section perpendicular to the center line O1 of the swivel chamber 212 gradually decreases from the position of the tip surface 15t of the valve seat member 15 or the upper end surface 21nu of the nozzle plate 21n toward the bottom surface 212d of the swivel chamber 212.

[0068] The fuel injection hole 220 is formed such that its cross-sectional area gradually decreases from the inlet opening 220i side to the outlet opening 220o side. That is, the inner circumferential surface 220c of the fuel injection hole 220, as viewed from the inlet opening 220i side, is formed in a shape that tapers along the direction of fuel flow. In other words, the fuel injection hole 220 has a tapered shape (tapered surface) when viewed from the inlet opening 220i side. Alternatively, the fuel injection hole 220 is formed in a shape that tapers from the inlet opening 220i side to the outlet opening 220o side. For this reason, the inner circumferential surface 220c of the fuel injection hole 220 is inclined with respect to the center line of the fuel injection hole 220.

[0069] In this embodiment, the center line of the fuel injection hole 220 coincides with the center line O1. That is, the fuel injection hole 220 is formed such that its center line O1 is perpendicular to the upper end surface 21nu of the nozzle plate 21n and the bottom surface 212d of the swivel chamber 212. However, the center line O1 of the fuel injection hole 220 may be inclined with respect to the upper end surface 21nu of the nozzle plate 21n and the bottom surface 212d of the swivel chamber 212.

[0070] The inner circumferential surface 220c of the fuel injection hole 220, due to its inclination, can guide the fuel coming from upstream towards the outlet opening 220o like a mortar and pestle. Furthermore, because the cross-sectional area is narrowest near the outlet opening 220o, the fuel flow velocity can be increased, promoting fuel splitting. As a result, atomization of the fuel spray injected from the fuel injection valve 1 can be promoted, improving the combustion efficiency of the engine.

[0071] In this embodiment, the inner circumferential wall 212c of the swirling chamber 212 is also inclined with respect to the center line O1 of the fuel injection hole 220, and the direction of inclination of the inner circumferential wall 212c of the swirling chamber 212 with respect to the center line O1 is the same as the direction of inclination of the inner circumferential surface 220c of the fuel injection hole 220. Therefore, the flow of fuel swirling in the swirling chamber 212 into the fuel injection hole 220 is made smoother, and the flow velocity of the fuel flowing into the fuel injection hole 220 can be increased. In this case, because the inner circumferential wall 212c of the swirling chamber 212 is inclined, the width W212d of the bottom surface 212d of the swirling chamber 212 is reduced, and the effect of smoothing the flow of fuel swirling in the swirling chamber 212 into the fuel injection hole 220 is improved.

[0072] Referring to Figure 6, the machining method for the swivel passage 210 and the fuel injection hole 220 will be described. Figure 6 is a schematic diagram showing the machining method for the section of the cross-section in the direction of arrow VV in Figure 4.

[0073] In this embodiment, the nozzle plate 21n is press-formed to create the swivel passage 210 and the fuel injection hole 220. An upper die (first die) 301 and a lower die (second die) 302 are used for the press-formed process. The upper die 301 has a press surface 301a that forms the inner circumferential wall 212c of the swivel chamber 212, a press surface 301b that forms the bottom surface 212d of the swivel chamber 212, and a press surface 301c that forms the inner circumferential surface 220c of the fuel injection hole 220 and punches out the outlet opening 220o of the fuel injection hole 220. The lower die 302 has a press surface 302a that forms the outer surface of the inner circumferential wall 212c of the slewing chamber 212, a press surface 302b that forms the outer surface of the bottom surface 212d of the slewing chamber 212, a press surface 302c that forms the outer surface of the inner circumferential surface 220c of the fuel injection hole 220, and a hole 302d for punching out the outlet opening 220o of the fuel injection hole 220. In addition, the upper die 301 and the lower die 302 are provided with press surfaces (not shown) for press-working the lateral passage 211.

[0074] In this embodiment, the nozzle plate 21n is press-formed using the upper die 301 and the lower die 302 to form the swivel passage 210 and the fuel injection hole 220. When the swivel passage 210 and the fuel injection hole 220 are formed by cutting with an end mill, a considerable amount of processing time is required for the cutting process. In this embodiment, by forming the swivel passage 210 and the fuel injection hole 220 by press-forming, the processing time can be significantly reduced. Furthermore, by transferring the withdrawal angle of the upper die during press-forming to the swivel passage 210 and the fuel injection hole 220, the inclined surfaces of the side walls 211b and 211c of the lateral passage 211, the inclined surface of the inner circumferential wall 212c of the swivel chamber 212, and the tapered surface of the fuel injection hole 220 can be formed simultaneously.

[0075] Referring to Figure 7, an internal combustion engine equipped with the fuel injection valve according to the present invention will be described. Figure 7 is a cross-sectional view of an internal combustion engine 100 equipped with the fuel injection valve 1.

[0076] An engine block 101 of the internal combustion engine 100 has a cylinder 102 formed thereon, and an intake port 103 and an exhaust port 104 are provided at the top of the cylinder 102. An intake valve 105 that opens and closes the intake port 103 is provided in the intake port 103, and an exhaust valve 106 that opens and closes the exhaust port 104 is provided in the exhaust port 104. An intake pipe 108 is connected to the inlet end 107a of an intake passage 107 formed in the engine block 101 and communicating with the intake port 103.

[0077] A fuel pipe 110 is connected to the fuel supply port 2 (see Figure 1) of the fuel injection valve 1.

[0078] A mounting portion 109 for the fuel injector 1 is formed in the intake pipe 108, and an insertion port 109a for inserting the fuel injector 1 is formed in the mounting portion 109. The insertion port 109a penetrates to the inner wall surface (intake passage) of the intake pipe 108, and the fuel injected from the fuel injector 1 inserted into the insertion port 109a is injected into the intake passage. In the case of bidirectional spray, for an internal combustion engine in which two intake ports 103 are provided in the engine block 101, each fuel spray is directed towards each intake port 103 (intake valve 105) and injected.

[0079] The fuel injection valve 1 of the above-described embodiment has the following features. (1) A valve body 17 and a valve seat 15b that work together to open and close the fuel passage, A swivel passage 210 and a fuel injection port 220 are provided downstream of the valve body 17 and valve seat 15b, Equipped with, The swivel passage 210 has a swivel chamber 212 in which a swivel passage for fuel is formed, and a lateral passage 211 connected to the upstream side of the swivel chamber 212. The fuel injection port 220 is formed such that its inlet opening 220i opens into the bottom surface 212d of the swirling chamber 212, and it is also formed in a shape that tapers from the inlet opening 220i side to the outlet opening 220o side.

[0080] (2) The inner circumferential wall 212c of the slewing chamber 212 is composed of an inclined surface that is inclined away from the inlet opening 220i of the fuel injection hole 220 as it moves away vertically from the side of the bottom surface 212d of the slewing chamber 212.

[0081] (3) The side walls 211b and 211c of the lateral passage 211 are composed of inclined surfaces such that the width of the lateral passage 211 increases as it moves away from the bottom surface 211d of the lateral passage 211 in the vertical direction.

[0082] (4) When we consider a first extension line 211ba, which is the extension of the boundary line between the bottom surface 211d of the lateral passage 211 and one side wall 211b of the lateral passage 211, and a second extension line 211ca, which is the extension of the boundary line between the bottom surface 211d of the lateral passage 211 and the other side wall 211c of the lateral passage 211, The second extension line 211ca is located on the side of the center O1 of the inlet opening 220i of the fuel injection hole 220 relative to the first extension line 211ba. The inlet opening 220i of the fuel injection port 220 is formed to extend beyond the second extension line 220ca and onto the side of the first extension line 211ba.

[0083] (5) The outlet opening 220o of the fuel injection hole 220 is formed to be on the opposite side of the first extension line 220ba from the second extension line 220ca.

[0084] (6) A valve seat member 15 on which a valve seat 15b is formed, A nozzle plate 21n is attached to the tip surface 15t of the valve seat member 15, Equipped with, The swivel chamber 212, the lateral passage 211, and the fuel injection hole 220 are formed on the surface 21nu of the nozzle plate 21n that faces the tip surface 15t of the valve seat member 15.

[0085] The fuel injection valve 1 of the above-described embodiment is manufactured by the following manufacturing method.

[0086] A valve body 17 and valve seat 15b work together to open and close the fuel passage, A swivel passage 210 and a fuel injection port 220 are provided downstream of the valve body 17 and valve seat 15b, Equipped with, The swivel passage 210 has a swivel chamber 212 in which a swivel passage for fuel is formed, and a lateral passage 211 connected to the upstream side of the swivel chamber 212. A fuel injection port 220 is formed such that the inlet opening 220i of the fuel injection port 220 opens to the bottom surface 212d of the swivel chamber 212, and is a method for manufacturing a fuel injection valve 1. The swivel chamber 212, the lateral passage 211, and the fuel injection port 220 are formed by press working. The fuel injection port 220 is formed in a shape that tapers from the inlet opening 220i side to the outlet opening 220o side.

[0087] It should be noted that the present invention is not limited to the embodiments and modifications described above, and it is possible to delete some components, add other components not described, or replace some components. [Explanation of Symbols]

[0088] 1...Fuel injector, 1a...Valve axis (central axis), 15b...Valve seat, 17...Valve body, 210...Swivel passage, 211...Lateral passage, 211b...One side wall of the lateral passage 211, 211ba...First extension line, 211c...Other side wall of the lateral passage 211, 211ca...Second extension line, 211d...Bottom surface of the lateral passage 211, 212...Swivel chamber, 212c...Inner circumferential wall of the swivel chamber 212, 212d...Bottom surface of the swivel chamber 212, 220...Fuel injection hole, 220c...Inner circumferential surface of the fuel injection hole 220, 220i...Inlet opening of the fuel injection hole 220, 220o...Outlet opening of the fuel injection hole 220, O1...Center of the inlet opening surface 220i of the fuel injection hole 220.

Claims

1. A valve body and valve seat that work together to open and close the fuel passage, A swivel passage and fuel injection port provided downstream of the valve body and the valve seat, Equipped with, The swirling passage comprises a swirling chamber in which a fuel swirling flow path is formed, and a lateral passage connected to the upstream side of the swirling chamber. The rotating chamber has a bottom surface which is made of a plane, and an inner circumferential wall formed around the bottom surface, The fuel injection port is formed such that its inlet opening opens to the bottom surface of the swirling chamber, and is tapered from the inlet opening to the outlet opening. The inner circumferential wall of the rotating chamber is composed of an inclined surface that is inclined in a direction away from the inlet opening of the fuel injection hole as it moves vertically away from the bottom surface of the rotating chamber. The side walls of the aforementioned lateral passage are composed of inclined surfaces such that the width of the lateral passage increases as it moves away vertically from the bottom surface of the lateral passage. The swirling passage is formed on the bottom surface between the inner circumferential wall of the swirling chamber and the inlet opening of the fuel injection hole. When we consider a first extension line, which is the extension of the boundary line between the bottom surface of the lateral passage and one side wall of the lateral passage, and a second extension line, which is the extension of the boundary line between the bottom surface of the lateral passage and the other side wall of the lateral passage, The second extension line is located on the center side of the inlet opening of the fuel injection hole relative to the first extension line. A fuel injection valve in which the inlet opening of the fuel injection hole is formed to extend beyond the second extension line and protrude towards the first extension line.

2. In the fuel injection valve according to claim 1, The fuel injection valve is formed such that the outlet opening of the fuel injection hole is located on the side opposite to the first extension line with respect to the second extension line.

3. In the fuel injection valve according to claim 2, The valve seat member on which the valve seat is formed, A nozzle plate attached to the tip surface of the valve seat member, Equipped with, The swivel chamber, the lateral passage, and the fuel injection hole are formed on the surface of the nozzle plate facing the tip surface of the valve seat member.

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