Fuel injector

Abstract

Fuel injector, comprising: a tubular housing (20) with a plurality of injection holes (31, 32) which are provided on one side in a direction of a central axis (CA0) and from which fuel is injected, a valve seat (34, 341, 342) which is formed around the plurality of injection holes, and a fuel passage (18) in which the fuel injected from the injection hole flows; a needle (40) which is provided such that it can be moved back and forth in the direction of the central axis of the housing, the needle being released from or in contact with the valve seat in order to open or close the injection hole; a coil (38) which forms a magnetic field when it is energized; a stator core (35) which is fixed in the housing in the magnetic field formed by the coil; and a movable core (47) which is provided such that it can be moved back and forth in the direction of the central axis of the housing, wherein the movable core together with the needle is attracted in the direction towards the stator core when the coil is energized, wherein: an outer opening (314, 324) of the injection hole at an outer wall (304) of the housing has an inner diameter which is larger than an inner diameter of an inner opening (313, 323) of the injection hole at an inner wall (303) of the housing; The valve seat, when a virtual plane (VP341, VP342) encompassing the valve seat is extended towards a central axis (CA0) of the housing, first intersects the first injection hole inner wall (311, 321) formed between the outer opening and the inner opening in order to enlarge a cross-sectional area of ​​the injection hole from the inner opening towards the outer opening; and an opening angle (β1, β2), which maximizes the transverse force, decreases, while an injection angle (α1, α2) of the injection hole increases, wherein the injection angle (α1, α2) corresponds to an angle formed by an injection hole axis (VL31, VL32) with the central axis of the housing, and wherein the opening angle corresponds to an angle formed by a first straight line (L311, L321), which connects the outer opening on the first injection hole inner wall with the inner opening, with a second straight line (L312, L322), which connects the outer opening on a second injection hole inner wall (312, 322), which is arranged on the opposite side to the first injection hole inner wall including the first straight line over the injection hole axis, which passes through an inner-wall-side center point (IP31, IP32) on the inner wall of the housing and a point on the central axis of the housing, with the inner opening connects, forms.

Description

Technical area

[0001] The present disclosure relates to a fuel injection valve for injecting and supplying fuel into or to an internal combustion engine. General state of the art

[0002] In a conventional fuel injector, an injection hole in a housing is opened and closed by the reciprocating motion of a needle to inject fuel outward within the housing. For example, JP 2007-085333 A describes a fuel injector provided with a housing having injection holes with different inner diameters, which are positioned according to the position of a spark plug.

[0003] In the fuel injection valve described in JP 2007-085333 A, the inner diameter of the injection hole is constant from an inner opening formed in the inner wall of the housing to an outer opening formed in the outer wall of the housing. Therefore, different amounts of fuel flow per unit time into the injection holes with different inner diameters. Therefore, fuel cannot be reliably atomized in a combustion chamber. Unatomized, droplet-like fuel injected from the injection hole easily leads to poor or incomplete combustion, potentially increasing the amount of particulate matter generated.

[0004] Further relevant prior art is disclosed in the documents JP 2005 - 106 006 A, JP 2009 - 103 035 A and DE 10 2009 047 704 A1. Summary of the invention

[0005] An object of the present disclosure is to provide a fuel injection valve capable of reducing the amount of particulates generated when burning fuel.

[0006] The above object is achieved by the subject matter of claim 1. Advantageous developments of the invention are the subject matter of the subsequent dependent claims.

[0007] According to an illustrative aspect of the present disclosure, the fuel injection valve includes a housing, a needle, a coil, a stator core, and a movable core. The housing includes a plurality of injection holes from which fuel is injected, a valve seat formed around the plurality of injection holes, an outer opening of the injection hole at an outer wall of the housing, an inner opening of the injection hole at an inner wall of the housing, and a first injection hole inner wall formed between the outer opening and the inner opening to increase a cross-sectional area of ​​the injection hole from the inner opening toward the outer opening.

[0008] In the fuel injection valve of the present disclosure, an inner diameter of the outer opening of the injection hole is larger than an inner diameter of the inner opening of the injection hole. When a virtual plane including the valve seat extends toward a center axis of the housing, the valve seat first intersects the first injection hole inner wall.Furthermore, in the fuel injection valve of the present disclosure, an opening angle is larger when an injection angle is smaller than an angle that an injection hole axis forms with the center axis of the housing, and the opening angle corresponds to an angle that a first straight line connecting the outer opening on the first injection hole inner wall to the inner opening forms with a second straight line connecting the outer opening on a second injection hole inner wall located on the opposite side to the first injection hole inner wall including the first straight line across the injection hole axis passing through an inner wall-side center point on the inner wall of the housing and a point on the center axis of the housing, to the inner opening.

[0009] In general, the degree of fuel atomization in a fuel injection valve is determined depending on the characteristics of the fuel flow in the injection hole. Specifically, the fuel is more easily atomized as the surface area of ​​the liquid fuel flowing in the injection hole in contact with the air increases and as the flow rate of the fuel flowing in the injection hole increases.

[0010] In the fuel injection valve of the present disclosure, an injection hole has a conical shape such that an outer opening of one injection hole has an inner diameter larger than an inner diameter of an inner opening of one injection hole. When injection hole inner walls are compared with each other in each of a plurality of injection holes formed between the outer opening and the inner opening to increase the cross-sectional area of ​​the injection hole from the inner opening toward the outer opening, an opening angle corresponds to an angle formed by a first straight line on the injection hole inner wall with a second straight line on the injection hole inner wall on the opposite side to the injection hole inner wall including the first straight line across the injection hole axis, and the opening angle becomes larger as an injection angle is smaller.

[0011] The injection angle of the injection hole is positively correlated with an impingement angle as an angle formed by a virtual plane including a valve seat and the injection hole inner wall of the injection hole. As the injection angle decreases, the flow rate of fuel flowing in the injection hole becomes higher. However, the impingement angle becomes smaller, and therefore, fuel is difficult to atomize. Therefore, in the fuel injection valve of the present disclosure, with respect to the injection hole having a relatively small impingement angle, that is, with respect to the injection hole having a relatively small injection angle, the opening angle is relatively increased to increase the surface area of ​​the liquid fuel flowing in the injection hole in contact with air.Consequently, in the fuel injection valve of the present disclosure, the fuel flowing along the injection hole inner wall of the injection hole can be easily atomized to reduce the amount of droplet fuel that generates particulates due to incomplete combustion. Short description of the figures

[0012] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings: Fig. 1 is a cross-sectional view illustrating a fuel injector according to an embodiment of the present disclosure; Fig. 2 an enlarged view showing a section II in Fig. 1 represents; Fig. 3 a view from the perspective of an arrow III in Fig. 2; and Fig. 4 is a characteristic diagram illustrating a relationship between an opening angle and an injection angle of the fuel injection valve according to the embodiment of the present disclosure. Description of embodiments

[0013] Embodiments of the present disclosure are described below with reference to the drawings. (Embodiment)

[0014] Fig. 1 and Fig. 2 illustrate a fuel injector 1 according to an embodiment of the present disclosure. Fig. 1 and Fig. 2 depict a valve opening direction in which a needle 40 is released from a valve seat 34 and a valve closing direction in which the needle 40 comes into contact with the valve seat 34.

[0015] The fuel injection valve 1 is used, for example, in a fuel injection device in a direct-injection gasoline engine (not shown) to inject gasoline fuel into and deliver it to the engine at a higher pressure. In this case, the engine corresponds to an internal combustion engine. The fuel injection valve 1 comprises a housing 20, the needle 40, a movable core 47, a stator core 35, a coil 38, a first spring 24, and a second spring 26.

[0016] As in Fig. 1, the housing 20 is configured from a first tubular member 21, a second tubular member 22, a third tubular member 23, and an injection nozzle 30. The first tubular member 21, the second tubular member 22, and the third tubular member 23 are each substantially cylindrical, and the first tubular member 21, the second tubular member 22, and the third tubular member 23 are coaxially connected to each other in this order.

[0017] The first tubular member 21 and the third tubular member 23 are made of a magnetic material, such as ferritic stainless steel, and the first tubular member 21 and the third tubular member 23 are magnetically stabilized. The first tubular member 21 and the third tubular member 23 have a relatively low hardness. The second tubular member 22 is made of a non-magnetic material, such as austenitic stainless steel, for example. The second tubular member 22 has a higher hardness than the first tubular member 21 and the third tubular member 23.

[0018] The injection nozzle 30 is provided on the first tubular member 21 on the opposite side to the second tubular member 22. The injection nozzle 30 is shaped like a tube with a closed end, made of metal such as martensitic stainless steel, and welded to the first tubular member 21. The injection nozzle 30 is quenched to have a predetermined hardness. The injection nozzle 30 is configured from an injection portion 301 and a tubular portion 302.

[0019] The injection portion 301 is linearly symmetrical about a central axis CA0 of the housing 20, which is coaxial with the central axis of the fuel injection valve 1. A first outer wall 304 of the injection portion 301 protrudes along the central axis CA0. The injection portion 301 has a plurality of injection holes connecting the interior and exterior of the housing 20. The valve seat 34 is formed at the edge of the inner opening, that is, an inner opening of the injection hole formed at an inner wall 303 of the injection portion 301.

[0020] The tubular portion 302 surrounds the outer radial side of the injection portion 301 and extends in the opposite direction to the direction in which the first outer wall 304 of the injection portion 301 protrudes. The tubular portion 302 has a first end connected to the injection portion 301 and a second end connected to the first tubular member 21.

[0021] The needle 40 is made of metal, such as martensitic stainless steel. The needle 40 is quenched to a predetermined hardness. The needle 40 has approximately the same hardness as the injection nozzle 30.

[0022] The needle 40 is accommodated in the housing 20 in such a way that it can be moved back and forth. The needle 40 is configured from a shaft portion 41, a sealing portion 42, and a large-diameter portion 43. The shaft portion 41, the sealing portion 42, and the large-diameter portion 43 are integrally formed.

[0023] The shaft portion 41 corresponds to a cylindrical rod. A sliding portion 45 is formed near the sealing portion 42 of the shaft portion 41. The sliding portion 45 is substantially cylindrical, and a portion of a second outer wall 451 is provided with a chamfer. A non-chamfered portion of the second outer wall 451 of the sliding portion 45 can slide on the inner wall of the injection nozzle 30. Accordingly, the needle 40 is guided at one end on the side of the valve seat 34 to reciprocate. The shaft portion 41 has an opening 46 connecting the inner wall to the outer wall of the shaft portion 41.

[0024] The sealing portion 42 is provided at the end of the shaft portion 41 on the side of the valve seat 34 so as to be able to contact the valve seat 34. At the needle 40, the sealing portion 42 is detached from the valve seat 34 or is in contact with the valve seat 34 to open or close the injection hole, thereby enabling or preventing communication between the inside and outside of the housing 20.

[0025] The large-diameter portion 43 is provided on the shaft portion 41 on the opposite side to the seal portion 42. The large-diameter portion 43 has a larger diameter than the shaft portion 41. An end surface of the large-diameter portion 43 on the valve seat 34 side is in contact with the movable core 47.

[0026] The needle 40 reciprocates in the housing 20 while the sliding portion 45 is supported by the inner wall of the injection nozzle 30 or the shaft portion 41 is supported by the inner wall of the second tubular member 22 via the movable core 47.

[0027] The movable core 47 is substantially cylindrical, made of a magnetic material, such as ferritic stainless steel, and coated or chrome-plated, for example. The movable core 47 is magnetically stabilized. The hardness of the movable core 47 is relatively low and approximately equal to the hardness of the first tubular member 21 and the third tubular member 23 of the housing 20. The movable core 47 has a through-hole 49 substantially at its center. The shaft portion 41 of the needle 40 is inserted into the through-hole 49.

[0028] The stator core 35 is substantially cylindrical and made of a magnetic material, such as ferritic stainless steel. The stator core 35 is magnetically stabilized. Although the stator core 35 has approximately the same hardness as the movable core 47 to serve as a stop for the movable core 47, the stator core 35 is coated with, for example, chromium to ensure the necessary hardness. The stator core 35 is welded to the third tubular member 23 of the housing 20 to be fixed to the inside of the housing 20.

[0029] The coil 38 is substantially cylindrical and mainly surrounds the outer radial side of the second tubular member 22 and the third tubular member 23. When electric power is supplied, the coil 38 forms a magnetic field. When the magnetic field is formed around the coil 38, the stator core 35, the movable core 47, the first tubular member 21, and the third tubular member 23 form a magnetic circuit. This generates a magnetic attraction force between the stator core 35 and the movable core 47, attracting the movable core 47 toward the stator core 35. At this time, the needle 40, which abuts against the surface of the movable core 47 on the opposite side to the valve seat 34, moves together with the movable core 47 toward the stator core 35, that is, in the valve-opening direction.

[0030] The first spring 24 is provided such that a first end contacts a spring contact surface 431 of the large-diameter portion 43. A second end of the first spring 24 contacts one end of a fitting tube 11 press-fitted into the stator core 35. The first spring 24 has an axially extending force. Therefore, the first spring 24 biases the needle 40 together with the movable core 47 toward the valve seat 34, that is, in the valve closing direction.

[0031] A first end of the second spring 26 is in contact with a first step surface 48 of the movable core 47. A second end of the second spring 26 is in contact with a second step surface 211, which is annular and formed on the inner wall of the first tubular member 21 of the housing 20. The second spring 26 has an axially extending force. Therefore, the second spring 26 biases the movable core 47 together with the needle 40 in the opposite direction to the valve seat 34, or the direction away from the valve seat 34, that is, the valve opening direction.

[0032] In the present embodiment, a displacement or biasing force of the first spring 24 is set to be greater than a biasing force of the second spring 26. Therefore, in the state where no electric power is supplied to the coil 38, the sealing portion 42 of the needle 40 is in contact with the valve seat 34, that is, in the valve-closed state.

[0033] A substantially cylindrical fuel introduction line 12 is press-fitted and welded into the end of the third tubular member 23 on the opposite side to the second tubular member 22. A filter 13 is provided on the inside of the fuel introduction line 12. The filter 13 collects foreign matter contained in the fuel flowing through an introduction port 14 of the fuel introduction line 12.

[0034] The outer radial sides of the fuel introduction pipe 12 and the third tubular member 23 are molded or overmolded using resin. A connector 15 is formed at the molding portion. A terminal 16 for supplying electric power to the coil 38 is overmolded at the connector 15. A tubular holder 17, which covers or encloses the coil 38, is provided on the outer radial side of the coil 38.

[0035] Fuel flowing through the introduction port 14 of the fuel introduction pipe 12 passes on the inner radial side of the stator core 35, in the fitting pipe 11, on the inside of the large-diameter portion 43 and the shaft portion 41 of the needle 40, in the opening 46, and a gap between the first tubular member 21 and the shaft portion 41 of the needle 40, and the fuel is introduced into the injection nozzle 30. That is, a portion from the introduction port 14 of the fuel introduction pipe 12 to the gap between the first tubular member 21 and the shaft portion 41 of the needle 40 forms a fuel passage 18, which introduces fuel into the injection nozzle 30. In order to inject fuel directly into a combustion chamber of the engine, the pressure of the fuel flowing in the fuel passage 18 is relatively high and set to 1 MPa or higher in the fuel injection valve according to the embodiment.

[0036] The fuel injection valve 1 according to the embodiment is characterized by the position and shape of injection holes formed at the injection nozzle 30. Here, with reference to Fig. 2, which corresponds to a cross-sectional view of the fuel injection valve 1 along the central axis CA0, the position and shape of the injection holes are described below.

[0037] First, the shape of a first injection hole 31 is described.

[0038] The first injection hole 31 is formed on the inner wall 303 of the injection portion 301 such that an angle formed by a first virtual line VL31 corresponding to an injection hole axis passing through a first inner wall-side center point IP31 located a predetermined first distance R1 from the center axis CA0 and a point on the center axis CA0 with the center axis CA0 becomes a first injection angle α1.

[0039] The first injection hole 31 has a circular cross-section perpendicular to the first virtual line VL31. A first outer opening 314 on the first outer wall 304 has an inner diameter larger than an inner diameter of a first inner opening 313 on the inner wall 303. That is, the first injection hole 31 is formed in a conical shape, so that the first injection hole 31 becomes smaller toward the inside of the injection nozzle 30 when viewed from outside the fuel injection valve 1.

[0040] In the first injection hole 31, the injection hole inner wall forms a first opening angle β1 between the first inner opening 313 and the first outer opening 314, so that the cross-sectional area of ​​the first injection hole 31 increases from the first inner opening 313 toward the first outer opening 314.

[0041] With reference to Fig. 2, which corresponds to a cross-sectional view of the fuel injection valve 1 along the central axis CA0 and the first virtual line VL31, the first opening angle β1 will be specifically described below. Here, for the sake of simplicity, the injection hole inner wall of the first injection hole 31, which is closer to the central axis CA0 than to the first virtual line VL31, is defined as a first injection hole inner wall 311, which corresponds to a first injection hole inner wall on which a first straight line is arranged, and the injection hole inner wall of the first injection hole 31, which is farther from the central axis CA0 than from the first virtual line VL31, is defined as a second injection hole inner wall 312, which corresponds to a second injection hole inner wall arranged on the opposite side to the first injection hole inner wall. At this time, as in Fig. 2, an angle formed by a first cross-sectional line L311 corresponding to the first straight line on the first injection hole inner wall 311 and a second cross-sectional line L312 corresponding to the second straight line on the second injection hole inner wall 312, to the first opening angle β1.

[0042] A first valve seat 341 corresponds to a portion of the valve seat 34 and is arranged on the opposite side to the center axis CA0 from the first injection hole 31. When a first virtual plane VP341 including the first valve seat 341 extends toward the center axis CA0, the first virtual plane VP341 first intersects the first injection hole inner wall 311. In other words, when the first virtual plane VP341 extends toward the center axis CA0, the first valve seat 341 directly intersects the first injection hole inner wall 311 without intersecting the second injection hole inner wall 312. At this time, as shown in Fig. 2, an angle that the first cross-sectional line L311 on the first injection hole inner wall 311 forms with the cross-sectional line on the first virtual plane VP341, to a first incident angle γ1 as an angle that the virtual plane forms with the injection hole inner wall forming the injection hole.

[0043] The shape of the second injection hole 32 is described below.

[0044] The second injection hole 32 is formed on the inner wall 303 of the injection portion 301 such that an angle formed by a second virtual line VL32 corresponding to an injection hole axis passing through a second inner wall-side center point IP32 located away from the center axis CA0 by a predetermined second distance R2 and a point on the center axis CA0 with the center axis CA0 becomes a second injection angle α2 which is smaller than the first injection angle α1.

[0045] The second injection hole 32 has a circular cross section perpendicular to the second virtual line VL32. A second outer opening 324 at the first outer wall 304 is larger than a second inner opening 323 at the inner wall 303. That is, the second injection hole 32 is formed in a conical shape, so that the second injection hole 32 becomes smaller toward the inside of the injection nozzle 30 when viewed from outside the fuel injection valve 1.

[0046] In the second injection hole 32, the injection hole inner wall forms a second opening angle β2 between the second inner opening 323 and the second outer opening 324, so that the cross-sectional area of ​​the second injection hole 32 increases from the second inner opening 323 toward the second outer opening 324.

[0047] With reference to Fig. 2, which corresponds to a cross-sectional view of the fuel injection valve 1 along the central axis CA0 and the second virtual line VL32, the second opening angle β2 is specifically described below. Here, the injection hole inner wall of the second injection hole 32, which is closer to the central axis CA0 than to the second virtual line VL32, is defined for convenience as a third injection hole inner wall 321, which corresponds to a first injection hole inner wall on which a first straight line is located, and the injection hole inner wall of the second injection hole 32, which is farther from the central axis CA0 than from the second virtual line VL32, is defined as a fourth injection hole inner wall 322, which corresponds to a second injection hole inner wall on the opposite side to the injection hole inner wall on which the first straight line is located. At this time, as in Fig. 2, an angle which the third cross-sectional line L321, which corresponds to the first straight line on the third injection hole inner wall 321, forms with the fourth cross-sectional line L322, which corresponds to the second straight line on the fourth injection hole inner wall 322, to the second opening angle β2.

[0048] A second valve seat 342 corresponds to a portion of the valve seat 34 and is arranged on the opposite side to the center axis CA0 from the second injection hole 32. When a second virtual plane VP342 including the second valve seat 342 is extended toward the center axis CA0, the second virtual plane VP342 first intersects the third injection hole inner wall 321 of the second injection hole 32. In other words, when the second virtual plane VP341 is extended toward the center axis CA0, the second valve seat 342 directly intersects the third injection hole inner wall 321 without intersecting the fourth injection hole inner wall 322. At this time, as shown in Fig. 2, an angle which the third cross-sectional line L321 on the third injection hole inner wall 321 forms with the cross-sectional line on the second virtual plane VP342, to a second incident angle γ2 as an angle which the virtual plane forms with the injection hole inner wall forming the injection hole.

[0049] Although the relationship between the injection angle, the opening angle and the impact angle is determined by only the two Fig. 2, other injection holes formed in the injection nozzle 30 have the same relationship. That is, the injection hole with a larger injection angle has a smaller opening angle and a larger incidence angle than the injection hole with a smaller injection angle.

[0050] Fig. 3 shows a fuel flow in an outward injection of fuel as viewed from the outside of the first injection hole 31 starting from the first injection hole 31. In Fig. 3, a direction of the central axis CA0 of the housing 20 with respect to the first injection hole 31 for describing the position of the fuel flowing in the first injection hole 31 is defined as a central axis side, and the opposite side to the central axis CA0 side of the housing 20 with respect to the first injection hole 31 is defined as an opposite central axis side.

[0051] When the needle 40 is separated from the first valve seat 341, fuel flows between the first valve seat 341 and a valve seat contact surface 421 of the sealing portion 42 and flows along the first virtual plane VP341 (see Fig. 2). As shown by an empty arrow F0, the fuel flowing along the first virtual plane VP341 hits the first injection hole inner wall 311. At this time, fuel is forced out by the back pressure in the fuel passage 18, and therefore, the fuel flows while being pressed or applied to the first injection hole inner wall 311, as shown in Fig. 3. Accordingly, fuel F1 flows into the first injection hole 31 while stalling at the first injection hole inner wall 311. However, since the fuel does not flow along the second injection hole inner wall 312 of the opposite center axis side, a space S31 is created on the opposite center axis side of the first injection hole 31.

[0052] In a fuel injection valve that injects fuel from the injection hole to atomize the fuel, it is desirable to apply a relatively large lateral force to the fuel flowing in the injection hole to improve fuel atomization. This lateral force acting on the fuel flowing in the injection hole is determined as a function of the product of the surface area of ​​the fuel flowing in the injection hole in contact with the air and the fuel flow rate.

[0053] In the fuel injection valve 1 according to the embodiment, the injection hole inner wall, among the injection hole inner walls forming the injection hole, which is located closer to the center axis CA0 includes the valve seat located on the opposite center axis side of the injection hole, and this intersects the virtual plane extending toward the center axis CA0. Therefore, when the needle 40 is detached from the valve seat 34 to form a gap (for example, a gap 300 in Fig. 2) between the valve seat 34 and a valve seat contact surface of the needle 40, the fuel flowing through the gap directly impacts the injection hole inner wall of the injection hole on the central axis CA0 side and flows while being pressed against the injection hole inner wall. Accordingly, the flow rate of the fuel decreases after the fuel flowing through the gap impacts the inner wall of the housing. As the impact angle increases, the fuel forced out through the gap between the valve seat 34 and the valve seat contact surface is more strongly urged against the injection hole inner wall. Consequently, the surface area of ​​the fuel in contact with the air, that is, a region indicated by a two-dot chain line A31 in Fig. 3 surrounding area is larger. Therefore, the fuel injection valve 1, in which fuel passing through the gap between the valve seat 34 and the valve seat contact surface directly impacts the injection hole inner wall of the injection hole on the center axis CA0 side, can atomize a relatively large amount of fuel.

[0054] In the fuel injection valve 1 according to the embodiment, the opening angle is adjusted according to the injection angle, which is positively correlated with the impact angle.

[0055] Fig. 4 shows a relationship between the injection angle and the opening angle of the injection hole in the fuel injection valve 1. Fig. Figure 4 shows a calculation of the opening angle that maximizes the lateral force based on a relationship between the opening angle and the lateral force acting on the injection hole at any injection angle.

[0056] As in Fig.As shown in Figure 4, the opening angle that maximizes the lateral force becomes smaller as the injection angle of the injection hole increases. That is, by using a large injection angle, even if the injection hole is formed such that the inner diameter of the inner opening is close to the inner diameter of the outer opening, the lateral force acting on the fuel becomes large, which easily atomizes the fuel. In contrast, when the injection angle is small, by forming the injection hole such that the inner diameter of the outer opening is larger than the inner diameter of the inner opening, the lateral force acting on the fuel can be increased. In this way, the opening angle is changed according to the injection angle, which atomizes a relatively large amount of fuel at each of the plurality of injection holes.

[0057] As described above, in the fuel injection valve 1 according to the embodiment, the fuel passing through the gap between the valve seat 34 and the valve seat contact surface can directly impact the injection hole inner wall on the central axis CA0 side among the injection hole inner walls constituting the injection hole, effectively utilizing the fuel pressure in the fuel passage 18 to increase the surface area of ​​the injection hole in contact with the air. Even in the injection hole with a relatively small impact angle, by increasing the opening angle, a relatively large lateral force can be exerted on the fuel urged against the injection hole inner wall to atomize a relatively large amount of fuel. Therefore, the fuel injection valve 1 according to the embodiment can atomize a relatively large amount of the fuel flowing in the injection hole.As fuel atomization is promoted, the amount of droplet fuel decreases, which reduces the amount of particles produced during fuel combustion. (Other embodiments) (i) In the above-mentioned embodiment, the injection hole is formed such that the opening angle becomes smaller as the incident angle becomes larger. However, the relationship between the incident angle and the opening angle is not limited to the above relationship. The virtual plane, which includes the valve seat on the opposite center axis side of the injection hole and extends toward the center axis CA0, must intersect the injection hole inner wall on the center axis side of the injection hole. (ii) In the above-mentioned embodiment, the pressure of the fuel flowing in the fuel passage is set to 1 MPa or higher. However, the fuel pressure is not limited to 1 MPa or higher. The pressure may be any pressure at which fuel can be directly injected into the combustion chamber of the engine. (iii) In the above-mentioned embodiments, the injection hole has a circular cross-section. However, the cross-sectional shape of the injection hole is not limited to a circle.

[0058] The present disclosure is not limited to the above-mentioned embodiments and can be applied to various embodiments within the spirit and scope of the present disclosure.

[0059] While the present disclosure has been described with reference to embodiments thereof, it should be understood that the disclosure is not limited to the embodiments and constructions. The present disclosure is intended to cover various modifications and equivalent arrangements. In addition, in addition to the various combinations and configurations, other combinations and configurations including more, fewer, or only a single element are also within the spirit and scope of the present disclosure.

Claims

[1] Fuel injection valve, comprising: a tubular housing (20) having a plurality of injection holes (31, 32) provided on one side in a direction of a central axis (CA0) and from which fuel is injected, a valve seat (34, 341, 342) formed around the plurality of injection holes, and a fuel passage (18) in which the fuel injected from the injection hole flows; a needle (40) provided so as to be reciprocable in the direction of the central axis of the housing, the needle being detached from the valve seat or being in contact with the valve seat to open or close the injection hole; a coil (38) which forms a magnetic field when energized; a stator core (35) which is fixed in the housing in the magnetic field formed by the coil; and a movable core (47) which is provided such that it can be moved back and forth in the direction of the central axis of the housing, the movable core being attracted together with the needle towards the stator core when the coil is energized, wherein: an outer opening (314, 324) of the injection hole at an outer wall (304) of the housing has an inner diameter which is larger than an inner diameter of an inner opening (313, 323) of the injection hole at an inner wall (303) of the housing; the valve seat, when a virtual plane (VP341, VP342) comprising the valve seat is extended toward a center axis (CA0) of the housing, first intersects the first injection hole inner wall (311, 321) formed between the outer opening and the inner opening to enlarge a cross-sectional area of ​​the injection hole from the inner opening toward the outer opening; and an opening angle (β1, β2) which maximizes the transverse force becomes smaller, while an injection angle (α1, α2) of the injection hole increases, wherein the injection angle (α1, α2) corresponds to an angle which an injection hole axis (VL31, VL32) forms with the central axis of the housing, and wherein the opening angle corresponds to an angle which a first straight line (L311, L321) which connects the outer opening on the first injection hole inner wall with the inner opening makes with a second straight line (L312, L322) which connects the outer opening on a second injection hole inner wall (312, 322) which is arranged on the opposite side to the first injection hole inner wall, including the first straight line across the injection hole axis which passes through an inner wall-side center point (IP31, IP32) on the inner wall of the housing and a point on the central axis of the housing is, connects with the inner opening, forms. [2] A fuel injection valve according to claim 1, wherein the injection hole is formed such that the injection hole with a larger injection angle has a smaller opening angle and a larger incidence angle (γ1, γ2) than the injection hole with a smaller injection angle, wherein the incidence angle corresponds to an angle that a virtual plane including a portion of a valve seat (341, 342) which is arranged on the opposite side to the center axis of the housing as viewed from the injection hole forms with the first injection hole inner wall of the injection hole. [3] A fuel injection valve according to claim 1 or 2, wherein a pressure of the fuel injected from the injection hole is 1 MPa or higher. [4] A fuel injection valve according to claim 1, wherein the valve seat, when the virtual plane (VP341, VP342) is extended toward the center axis of the housing, directly intersects the first injection hole inner wall (311, 321) without intersecting the second injection hole inner wall (312, 322).

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