JP3928851B2 - Fuel injection nozzle - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a fuel injection nozzle used for a fuel injection valve of an internal combustion engine.
[0002]
[Prior art]
In gasoline engines such as automobiles, gasoline as normal fuel is injected as a spray from a fuel injection nozzle into an intake pipe. However, in recent years, a gasoline direct injection system that injects fuel directly from a fuel injection nozzle into a combustion chamber has been developed for the purpose of low fuel consumption and low emission. A fuel injection nozzle used in a gasoline fuel direct injection system is required to be able to control the properties of spray (dispersibility, penetration force, etc.) according to the operating state (operating load and rotational speed) of the gasoline engine.
[0003]
That is, there are a homogeneous combustion operation and a stratified combustion operation in the operation state of the gasoline engine. The homogeneous combustion operation obtains a large output when a high load is applied, such as during high-speed running or acceleration. As shown in FIG. 14, gasoline is injected from the fuel injection nozzle 100 into the combustion chamber 103 during intake, that is, when the piston 102 descends in the cylinder 101. Therefore, it is required that the spray dispersibility is high and the penetration power is large.
[0004]
Gasoline is injected while the piston 102 is in the descending process and the pressure in the combustion chamber 103 is close to atmospheric pressure (about 0.1 MPa). Gasoline and air are mixed well and the whole is made to have the same air-fuel ratio (homogeneous), and then the air-fuel mixture (mixed gas of fuel and air) is ignited by the spark plug 104. The air-fuel mixture burns near the stoichiometric air-fuel ratio, and a large output can be obtained.
[0005]
On the other hand, stratified combustion operation improves fuel efficiency when a moderate or low load is applied, such as during steady running or idling. As shown in FIG. 15, gasoline is injected into the combustion chamber 103 in the latter half of the compression of the air-fuel mixture, that is, when the piston 102 rises in the cylinder 101. Therefore, it is required to control the dispersibility of the spray (compact) and to have a low penetration force.
[0006]
By injecting gasoline in a state where the piston 102 is in the ascending process and the pressure in the combustion chamber 103 is high (about 0.5 MPa) and delaying the injection timing, before the gasoline diffuses throughout the combustion chamber 103, the spark plug 104 An air-fuel mixture with a concentration that easily ignites is formed in the vicinity of the fuel, and an air layer without gasoline is formed around it. In this way, low fuel consumption is achieved by making the air / fuel mixture extremely lean as a whole.
[0007]
FIG. 16 shows an example of a fuel injection nozzle used in a conventional gasoline direct injection system. The fuel injection nozzle includes a nozzle body 110, a needle valve 115, an orifice plate 120, and a sleeve 125.
[0008]
The nozzle body 110 includes an inner peripheral wall surface 112 defining a fuel passage (nozzle hole) 111 and an annular valve seat 113 formed thereon. The needle valve 115 includes an outer peripheral wall 116 that faces the inner peripheral wall 112 and an annular valve portion 117 that is formed thereon and can be seated on the valve seat 113. When the needle valve 115 is moved in the axial direction in the nozzle body 110, the valve portion 117 is seated on or separated from the valve seat 113.
[0009]
The orifice plate 120 includes a bottom 121 and a circumferential wall 122. The bottom 121 includes a plurality of injection holes (orifices) 123 facing the downstream opening of the nozzle hole 111, and is attached to the nozzle body 110 at a circumferential wall 122. The sleeve 125 includes a base portion 126 and a cylindrical portion 127, and is attached to the nozzle body 110 and the orifice plate 120 in the cylindrical portion 127. The base 126 has a hollow hole 128 that faces the downstream side of the orifice 123.
[0010]
Fuel supplied from a fuel pump (not shown) flows into the nozzle hole 111 when the valve part 117 is separated from the valve seat 113, and is injected from the orifice 123 to become spray.
[0011]
[Problems to be solved by the invention]
  As can be seen from the above conventional example,homogeneousSince the required spray differs between combustion and stratified combustion, it has been extremely difficult to obtain a spray that can achieve both of these.
[0012]
The present invention has been made in view of the above circumstances, and is used in a direct-injection gasoline engine. It can effectively suppress the dispersibility and penetration of the spray during stratified combustion, and can achieve the necessary dispersibility of the spray during homogeneous combustion. An object of the present invention is to provide a fuel injection nozzle capable of providing a penetrating force.
[0013]
[Means for Solving the Problems]
While the inventors of the present application have studied the structure of the nozzle hole (hole diameter and dimension in the plate thickness direction) and the properties of the spray (dispersibility and penetration force), if the nozzle hole structure is in a certain condition, the injection atmosphere It was noticed that the shape of the spray injected from the nozzle hole differs depending on the pressure. It is a basic feature of the present invention that means for changing the spray dispersibility and penetration force between the homogeneous operation and the stratified operation is provided by utilizing the difference in the spray spray shape.
[0014]
A fuel injection nozzle according to the present invention includes a nozzle body in which an annular valve seat is formed on an inner peripheral wall surface defining a nozzle hole, and an annular outer peripheral wall surface facing the inner peripheral wall surface. A needle valve in which the valve portion is formed and moved in the axial direction so that the valve portion is separated from and seated on the valve seat; an inner circumference that is attached to the nozzle body and is located downstream of the plurality of nozzle holes facing the nozzle holes And a sleeve having a collision portion on which a spray of gasoline directly injected from a nozzle hole into a combustion chamber during stratified combustion collides.
[0015]
In the fuel injection nozzle of the present invention, the gasoline spray directly injected from the nozzle hole into the combustion chamber collides with the collision portion of the sleeve. The impingement portion changes the spray diffusion direction radially inward and downstream, thereby suppressing dispersibility (compacting). In addition, the collision part takes away a part of the kinetic energy of the spray at the time of the collision and suppresses the penetration force. Thereby, the spray pattern suitable for stratified combustion is formed.
[0016]
In addition, JSME Lecture Collection No. No. 3-99 discloses “a spray shape caused by an annular wall collision of an ultrahigh pressure fuel jet”. According to this, in a direct-injection diesel engine, the time from the start of injection to ignition is very short. Therefore, in order to improve fuel consumption and reduce harmful gases, formation of an air-fuel mixture during ignition is important. Considering this, an annular wall surface is formed around the perforated nozzle in order to disperse quickly after forming the spray and to form a uniform air-fuel mixture. By causing the jet of fuel to directly collide with the annular wall surface, collision with the wall surface of the combustion chamber is avoided and rapid spray formation is achieved.
[0017]
However, in a direct injection diesel engine, it is not indispensable to control the air-fuel mixture according to the operating load in the first place, and it cannot be identified with a direct injection gasoline engine.
[0018]
  The fuel injection nozzle according to claim 1 does not collide with the collision part when the spray of gasoline is injected into the combustion chamber at the time of homogeneous combustion. According to the fuel injection nozzle, a large spray dispersibility and penetration force are ensured during homogeneous combustion.
[0019]
  Claim2The fuel injection nozzle according to claim 1, wherein the collision portion is located 2 to 5 degrees upstream of the extension of the axis of the injection hole, and a part of the spray injected during stratified combustion is a collision portion. Crash weakly. According to this fuel injection nozzle, a spray pattern in which dispersibility and penetration force are suppressed to some extent is formed.
[0022]
  Claim3The fuel injection nozzle according to claim2In this case, the plurality of collision parts having different inner diameters and separated in the upstream and downstream directions are aligned on an extension of the axis of the nozzle hole. According to this fuel injection nozzle, the number of collisions (opportunity) of the spray to the collision part increases, and the dispersibility and penetration force are more effectively suppressed.
[0023]
  Claim4The fuel injection nozzle according to claim3In FIG. 2, each collision part is composed of an annular corner. According to this fuel injection nozzle, the corner portion defined by the inner peripheral surface parallel to the axis and the lower end surface orthogonal to the axis can reliably reflect the spray and suppress the spray dispersibility and penetration force.
[0024]
  Claim5In the fuel injection nozzle according to claim 1, the injection hole is formed in an injection hole plate attached to the nozzle body. According to this fuel injection nozzle, a plurality of injection holes can be formed in a desired pattern.
[0025]
  Claim6The fuel injection nozzle according to claim5The ratio t / d between the thickness of the nozzle hole plate and the hole diameter of the nozzle hole is 0.5 to 2.0. According to this fuel injection nozzle, large dispersibility and penetration of spray can be secured during homogeneous combustion, and dispersibility and penetration can be suppressed during stratified combustion.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
<Internal combustion engine, fuel>
  The fuel injection nozzle of the present invention is used in an internal combustion engine to inject a spray of gasoline directly into a combustion chamber. A typical internal combustion engine includes an automobile engine, but is not limited thereto.
<Nozzle body, Needle valve>
  In the present invention, since the nozzle body 110 and the needle valve 115 of FIG. 16 can be used, reference is appropriately made as necessary.
[0027]
The orifice plate 10 includes a circular bottom portion 11 and a cylindrical wall portion (not shown) around it, and a plurality of injection holes (orifices) 12 are formed in the bottom portion 11. The thickness t of the bottom 11 can be 0.1 to 0.4 mm.
(2) The number of orifices 12 is determined in consideration of the required injection amount and spray characteristics (shape and atomization) and can be 4 to 30. The plurality of orifices 12 can be arranged at equal intervals or different intervals in the circumferential direction on a locus of a circle having a predetermined radius centered at the center of the bottom portion 11. In addition to this, for example, they can be arranged in a lattice pattern or randomly. The distance from the center of the bottom 11 to the orifice 12 can be 0.05 to 0.20 mm.
(3) The hole diameter d of the plurality of orifices 12 is determined in consideration of the required injection amount and the number of orifices, and can be 0.06 to 0.40 mm. The hole diameters of all the orifices 12 may be equal, or a part of the hole diameters may be larger or smaller than the remaining hole diameter. The cross-sectional shape perpendicular to the axis of the orifice 12 may be a circular shape, or other shapes (for example, an elliptical shape or an oval shape).
(4) As a result of the plate thickness t of the bottom portion 11 and the hole diameter d of the orifice 12, the ratio t / d of the plate thickness t to the hole diameter d is 0.25 to 6.67. In order to improve spray dispersibility, it is desirable to reduce the value of t / d during homogeneous combustion. However, considering the suppression of dispersibility during stratified combustion, the value of t / d is preferably 0.50 to 2.0. The length of the orifice 12 is determined by the thickness t of the bottom 11 and the inclination angle α of the orifice 12, and is represented by t / sin α.
(5) Each orifice 12 is moved away from the axis L of the bottom 11 as it goes from the upper surface (upstream side) to the lower surface (downstream side) of the bottom 11, that is, to make a predetermined inclination angle α with respect to the axis L. It is inclined to. The inclination angle α is determined in consideration of the spray shape, and can be set to, for example, 0 to 30 degrees. Although the inclination angles α of all the orifices 12 can be made equal, the inclination angles α of some of the orifices 12 can be made larger or smaller than those of the rest.
(6) It should be noted that each orifice 12 has an outlet (downstream opening) located on a straight line extending from the center of the bottom 11 and the inlet (upstream opening) of the orifice 12, in other words, radially outward. It is desirable to extend in the direction. However, some of the orifices 12 can be formed in other directions.
<Sleeve (when there is one collision part)>
(1) The sleeve 15 attached to the nozzle body has a hollow hole 16, and the inner peripheral wall surface 17 of the hollow hole 16 has an annular collision part 20. In FIG. 1, the collision portion 20 includes a corner portion (edge portion) 21 having a right-angle cross-sectional shape that is defined by an inner circumferential surface in the axial direction and a distal end surface (lower end surface) in the radial direction.
[0028]
However, the collision part 20 can be provided with a throttle part having a reduced inner diameter at the lower end part. Specifically, the collision portion 25 having an annular shape and a triangular cross section as shown in FIG. 2A, the collision portion 26 having an annular shape and a rectangular cross section as shown in FIG. 2B, and FIG. An annular collision section 27 having a circular arc shape as shown may be provided. In addition, you may form two or three of these collision parts 26, 27, and 28 in an axial direction.
[0029]
Instead of providing a constriction at the lower end of the collision portion 20, a plurality of fan-shaped moving members 28 may be arranged so as to be movable in the radial direction with respect to the sleeve 15, as shown in FIG. good.
(2) Regarding the position of the corner 21, the radial distance from the axis L can be 0.9 to 1.5 A where A is the distance to the extension of the axis of the nozzle hole. Further, the distance in the axial direction from the lower surface of the bottom 11 of the corner 21 can be 0.6 to 1.2 B, where B is the distance to the extension of the axis of the nozzle hole. Furthermore, the axial length (height) of the corner portion 21 can be 0.2 to 1.0 B as the distance B to the extension line of the axis of the nozzle hole.
[0030]
The distance of the corner portion 21 from the downstream opening of the orifice 12 can be selected from 5d to 30d. If this distance is smaller than 5d, the effect of changing the nozzle hole direction is not sufficient, and if it is larger than 30d, it is difficult to specify the collision position.
(3) The positional relationship between the extension line 1 of the axis of the orifice 12 and the corner 21 is as follows. The relative position of both is determined by the inclination angle α of the orifice 12, the radial distance from the axis L of the corner portion 21, the axial distance from the bottom surface of the bottom portion 11, and the like. The corner 21 can be located downstream of the extension line l, on the extension line, or upstream of the extension line l.
[0031]
When the corner 21 is located downstream of the extension line l (first type, indicated by a point H in FIG. 1), an angle (intersection angle) formed by a straight line connecting the corner 21 and the orifice 12 with the extension line l Can be a few degrees. If the angle 21 is positioned too downstream, all the sprays collide with the corner 21 and the dispersibility and penetration deteriorate too much.
[0032]
The corner 21 can also be located on the extension line l (second type, illustrated by point I in FIG. 1).
[0033]
When the corner portion 21 is on the upstream side of the extension line l, it is particularly desirable that the crossing angle formed by the straight line connecting the orifice 12 and the corner portion 21 with respect to the extension line l is 0 to 2 degrees (third type, The case of 2 degrees is indicated by point J). It is desirable that the crossing angle is 2 to 5 degrees (the fourth type, the case of 5 degrees is indicated by K).
[0034]
  On the other hand, when the crossing angle is larger than 5 degrees, the corner 21 is too far away from the extension line l to the upstream side.
<4> The corner portion 21 is preferably formed over the entire circumference of the sleeve 15. However, it is not indispensable to do so. For example, as shown in FIG.Collision part31 or only within a predetermined angular range separated in a plurality of circumferential directions as shown in FIG.Collision part32 can also be formed.
<Formation of spray (in the case of a single collision part of the sleeve)>
  As described above, the direct injection type gasoline engine has a uniform combustion mode according to the operating state.combustionOr switch to stratified combustion.
(Homogeneous combustion)
<1> The pressure in the combustion chamber 103 during the fuel injection period during homogeneous combustion is a state in which the piston is close to the bottom dead center and close to atmospheric pressure (0.1 MPa). Therefore, the diffusion of the spray injected from the orifice 12 is not easily affected by the ambient pressure. The spray has a substantially cylindrical shape and proceeds from the extension line l of the axis of the orifice 12 to a range close to (below or above) the extension line.
[0035]
  The spray may collide with the corner 21 of the collision portion 20 of the sleeve 15 or may not collide. Whether to collide depends on the positional relationship between the extension line l and the corner 21.
<2> The collision occurs when the corner portion 21 is the first type or the second type. About a half of the spray hits the corner 21 and is reflected by the corner 21 inward in the radial direction and downstream. As a result, the dispersibility is slightly reduced, the penetration force is slightly reduced, and a spray pattern as shown in FIG. 4A is obtained (first mode). In the case of the first mode, only a part to about half of the spray sprayed collides with the corner 21 and is a moderate collision because it is weak.
<3> When the corner 21 is the third type and the fourth type, the spray hardly collides with the corner 21 or does not collide (second mode). Therefore, diffusion is mainlyCombustion chamberThe spray pattern is as shown in FIG. In the case of the second mode, the dispersion degree of spray can be increased by selecting a small ratio t / d between the thickness t of the bottom 11 and the hole diameter d of the orifice 12. For this purpose, the plate thickness t of the bottom 11 may be reduced and the hole diameter d of the orifice 12 may be increased.
  (Stratified combustion)
<1> The pressure in the combustion chamber 103 during the fuel injection period during stratified combustion is 0.4 to 0.6 MPa, for example, 0.5 MPa. In this case, the radial and axial diffusion of the spray is easily influenced by the pressure in the combustion chamber 103. As a result, the injection strength of the spray injected from the orifice 12 becomes weaker than that during homogeneous combustion, and proceeds slightly upstream (indicated by an arrow Y in FIG. 1) from the extension line l. As a result, the spray collides with the corner portion 21 with a higher probability than during homogeneous combustion and is reflected. However, there is a case of a strong collision and a case of a weak collision.
<2> A strong collision occurs when the corner 21 is of the third type. In this case, since the corner portion 21 is close to the extension line l and is in front of the traveling direction of the spray, most of the spray collides with the corner portion 21 and is reflected radially inward and downstream than before. . As a result, the dispersibility of the spray is greatly reduced. Moreover, a part of kinetic energy is lost at the time of a collision, and penetrating force is greatly suppressed. As a result, the spray pattern shown in FIG.
<3> When the corner 21 is the fourth type, the spray collides weakly with the corner 21. That is, since it is a little away from the extension line l of the corner 21 and slightly above the front in the spraying direction, only a part of the spray collides with the corner 21 and the remaining part of the spray does not collide with the corner 21. Along with this, the traveling direction of part of the spray is changed radially inward and downstream, and the dispersibility is reduced to some extent. Moreover, a part of kinetic energy is lost at the time of a collision, and penetration force is suppressed to some extent. As a result, the spray pattern shown in FIG.
[0036]
  In addition, when the corner | angular part 21 is a 1st type and a 2nd type, all the sprays collide strongly with the corner | angular part 21, and a dispersibility and penetration force fall too much.
(Summary)
  In summary, the collision part 20, that is, the corner part 21 isH pointFromPoint IIf it is arranged between the two, the spray hits the corner portion 21 weakly or moderately during homogeneous combustion, and hits too strongly during stratified combustion. Also, the corner 21Point IFromPoint JIf it arrange | positions between these, a spray will collide weakly at the corner | angular part 21 at the time of homogeneous combustion, or does not collide, but collides strongly at the time of stratified combustion. In addition, the corner 21Point JFromK pointsIf it arrange | positions between these, spray does not collide with the corner | angular part 21 at the time of homogeneous combustion, but collides weakly at the time of stratified combustion.
[0037]
  As shown in FIGS. 3A and 3B,Collision partWhen 31 and 32 are formed only in the semicircular circumference of the sleeve 15 or in a predetermined angular range separated in a plurality of circumferential directions, the spray is reflected only at a portion where the collision portions 31 and 32 are formed. As a result, the fuel is homogeneous and homogeneous.CornerIt is reflected only at the portion where 21 is formed, resulting in a spray pattern as shown in FIGS.
<Sleeve (when there are multiple collision parts)>
(Composition of collision part)
<1> The number of the plurality of collision parts can be 2 to 10. For example, as shown in FIG. 7, when the two collision parts 35 and 38 have the corner | angular parts 36 and 39, both corner | angular parts 36 and 39 are arrange | positioned on a concentric circle and a little apart in the fuel flow direction. In this case, the inner diameter of the first corner portion 36 on the downstream side is larger than the inner diameter of the second corner portion 39 on the upstream side. For example, when the inner diameter of the first corner portion 36 is D, the inner diameter of the second corner portion 39 can be 0.7 to 0.99D. When forming the third corner, the relationship between the second corner 39 and the third corner can be the same as the relationship between the first corner 36 and the second corner 39. The inner diameter of the first corner portion 36 may be larger or smaller than the inner diameter of the corner portion 21.
[0038]
Further, the axial length (height) of the first collision unit 35 on the downstream side may be longer or shorter than the height of the second collision unit 38 on the upstream side. When the height of the 1st collision part 35 is set to H, the height of the 2nd collision part 38 can be 0.5 to 2H. When forming the third collision part, the relationship between the second collision part 38 and the third collision part can be the same as the relationship between the first collision part 35 and the second collision part 38.
(2) It is desirable that the first corner portion 36 and the second corner portion 39 satisfy the same relationship as the relationship between the corner portion 21 and the extension line 1 with respect to the extension line l. That is, the first corner portion 36 may be located on the downstream side of the extension line l, on the extension line, or on the upstream side of the extension line. The radial distance from the axis L of the first corner 36 and the axial distance from the lower surface of the bottom 11 can be made larger or smaller than that of the corner 21.
[0039]
Similarly, the second corner portion 39 may be located on either the downstream side or the upstream side with respect to the extension line l. The same applies when forming the third corner.
(3) The first intersecting angle and the second intersecting angle formed by the extension line l, the straight line connecting the orifice 12 and the first corner 36, and the straight line connecting the orifice 12 and the second corner 39 are the same. Good or different. When both crossing angles are equal, the first corner portion 36 and the second corner portion 39 are located on the same straight line. On the other hand, if the crossing angle between the first corner portion 36 and the second corner portion 39 is different, one corner portion is closer to the extension line than the other corner portion, or is separated from the extension line.
(4) The shape of the collision part other than the corner part is shown in FIG. The collision part 41 in FIG. 8 (a) is made up of an uneven portion 42 having an annular shape and a semicircular cross section, and the collision part 44 in FIG.
[0040]
The collision part can be moved in the axial direction. For this purpose, for example, a cylindrical member having a collision part composed of a plurality of corners may be attached to the sleeve 15 for axial movement. By moving the cylindrical member in the axial direction, it is possible to change the collision position of the spray to the collision part and change the dispersibility and penetration force of the spray.
(Formation of spray)
(1) In FIG. 7, when the first crossing angle and the second crossing angle are equal, a part of the spray is reflected by the second corner 39 during the homogeneous combustion and the stratified combustion, and a part of the remaining spray is Reflected by the first corner 36. Thus, the increase in the number of times of collision and reflection at the sleeve 15 reduces the dispersibility of the spray and also reduces the penetration force.
[0041]
  When one corner is closer to the extension line than the other corner, the corner near the extension line l is more sprayed than the corner far from the extension line l in both homogeneous and stratified combustion. To reflect. For example, if the second corner portion 39 is brought closer to the extension line l than the first corner portion 36, a lot of spray is reflected at the second corner portion 39 and a little spray is reflected at the first corner portion 36. The
(Summary)
  In summary, the corners 36 and 39 areH pointFromPoint IDuringPoint IFromPoint JOrPoint JFromK pointsIn the case of being located between the two, the presence / absence of the collision of the spray with the collision part and the strength of the collision are basically the same as in the case of the single collision part 21 during the homogeneous combustion and the stratified combustion. However, according to the sleeve having the plurality of collision portions 35 and 38, the number of times the spray collides with the collision portions 35 and 38 increases, and the dispersibility and penetration force are more effectively suppressed accordingly.
[0042]
【Example】
Embodiments of the present invention will be described below with reference to the accompanying drawings.
(Configuration of Example)
FIG. 9 shows an embodiment of the present invention. The fuel injection nozzle according to this embodiment includes the nozzle body 110, the needle valve 115, the orifice plate 50, and the sleeve 55.
[0043]
  The orifice plate 50 is made of a thin metal plate and includes a bottom 51 and a cylindrical wall (not shown) as in the conventional example. bottom51Twelve orifices 52 are formed on a locus of a circle having a center with a predetermined radius. Each orifice 52 is formed in a radial shape that proceeds radially outward as it proceeds from the upstream side to the downstream side. The angle formed by the orifice 52 with respect to the axis L of the bottom 51 is 45 degrees. The ratio t / d between the thickness t of the bottom 51 and the hole diameter d of the orifice 52 is 1.3.
[0044]
The sleeve 55 includes a base portion 56 and a cylindrical portion (not shown) as in the conventional example, and is attached to the nozzle body 110 at the cylindrical portion. A hollow hole 58 is formed at the center of the base portion 56, and the inner peripheral wall surface 57 has an inner diameter that increases stepwise (three steps) as it advances from the upstream side to the downstream side. As a result, the first collision part 61, the second collision part 64, and the third collision part 67 are formed in order from the downstream side. The first collision portion 61 includes a first corner portion 62 having an annular shape and a right section, which is defined by an inner peripheral surface parallel to the axis L and a lower end surface perpendicular to the axis L. The first corner portion 62 has a radius r1 from the axis L, a height h1, and a distance from the bottom surface of the bottom portion 51.
[0045]
  The second corner portion of the second collision portion 64 that is annular and has a right-angled cross section65Is r2 whose radius from the axis L is smaller than r1 and whose height is h2 which is lower than h1 and whose distance from the lower surface of the bottom 51 is l2 which is shorter than l1. In addition, the third corner portion 68 provided in the third collision portion 67 and having a right-angled cross section has a radius r3 smaller than the above-described r2 and a height h3 lower than the above-mentioned h2 and a height of the bottom portion 51. The distance from the lower surface is l3 shorter than l2.
[0046]
As a result of the combination of the above distances and lengths, a straight line connecting the orifice 52 and the first corner 62, a straight line connecting the orifice 52 and the second corner 65, and the orifice 52 and the third with respect to the extension line l. The straight lines connecting the corners 68 form the same angle (about 2 degrees). Therefore, the 1st corner | angular part 62, the 2nd corner | angular part 65, and the 3rd corner | angular part 68 are on the same straight line, and are located a little upstream of the extension line l.
(Effect of Example)
In order to confirm the effect of this example, the following experiment was conducted. Fuel (dry solvent) having a pressure of 12 MPa was supplied into the fuel injection nozzle and injected into two sealed spaces having different pressures from the orifice 52 for 3 ms. The pressure in the first sealed space is a pressure of 0.1 MPa, and corresponds to the pressure in the combustion chamber 103 during homogeneous combustion. The pressure in the second sealed space is 0.5 MPa, which corresponds to the pressure in the combustion chamber 103 during stratified combustion.
[0047]
Since the pressure in the first sealed space is low, as shown in FIG. 10, the spray injected from each orifice 52 is hardly affected by the pressure, and proceeds and diffuses in a range extending slightly downstream from the extension line l. Therefore, the spray hardly collides with the third corner portion 68, the second corner portion 65, and the first corner portion 62, and is only a part even when colliding.
[0048]
FIG. 12 shows changes in the properties of the spray injected into the first sealed space. FIGS. 12 (a), 12 (b) and 12 (c) show states after 1 ms, 2 ms and 3 ms have elapsed from the start of injection, respectively. After a lapse of 1 ms from the start of injection, the spray is dispersed small and the penetration force is about 20 mm. Further dispersion occurs after 2 ms, and the penetration force is about 35 to 40 mm. After 3 ms, it is further dispersed, and the penetration force is about 45-50 mm.
[0049]
The sprays ejected from the orifices 52 further collide with each other, and a large dispersibility is obtained. Moreover, there is almost no loss of kinetic energy due to the collision. Accordingly, an ideal spray pattern having a conical shape having a large dispersibility and penetration force is formed.
[0050]
  On the other hand, since the pressure in the second sealed space is high, as shown in FIGS. 11A and 11B, the spray injected from each orifice 52 is pushed outward in the radial direction (see arrow Z). As a result, a considerable portion of the spray is third.Corner68, secondCorner65 and 1stCornerIt collides with 62 and is reflected. That is, a part of the spray collides with the third corner portion 68 and is reflected radially inward and downstream (see arrow P1). And part of the kinetic energy is lost in the event of a collision.
[0051]
Further, a part of the remaining spray collides with the second corner portion 65 and is reflected radially inward and downstream (see arrow P2). Further, a part of the remaining spray collides with the first corner portion 62 and is reflected radially inward and downstream.
[0052]
FIG. 13 shows the properties of the fuel injected into the second sealed space. FIGS. 13 (a), 13 (b) and 13 (c) show states after 1 ms, 2 ms and 3 ms have elapsed from the start of injection, respectively. In 1 ms after the start of injection, there is not much dispersion, and the penetration force is about 20 mm. In addition, dispersion does not progress even after 2 ms, and the penetration force is about 40 mm. Further, dispersion does not progress even after 3 ms, and the penetration force is about 60 mm. These dispersibility and penetrating force are smaller than the dispersibility and penetrating force when jetting into the first sealed space.
As a result, an ideal spray pattern that is compact and elongated with reduced dispersibility and penetration is formed.
[0053]
The first, second, and third corners 62, 65, and 68 are perpendicular to each other in cross section, and the spray on the upstream side of the corner edge is reflected, but the spray on the downstream side is not reflected, and a predetermined spray pattern is formed. It is convenient in obtaining. Further, since the first, second, and third corners 62, 65, and 68 have the above shape, the sleeve 55 including the first, second, and third collision portions 61, 64, and 67 is easy to form. .
(Reference example)
A first reference example, a second reference example, a third reference example, and a fourth reference example in which the positional relationship of the first corner portion 62, the second corner portion 65, and the third corner portion 68 with respect to the extension line l is different from that of the above embodiment. And the same test as the above example was conducted. In the first reference example, the first corner portion 62 is located at a point B (about 2 degrees upstream) in FIG. 9, and in the second reference example is located at a point C (about 4 degrees upstream). In the reference example, it is located at point D (about 6 degrees upstream), and in the fourth reference example, it is located at point E (more than 6 degrees upstream). In the first to fourth reference examples, the dimensions and shapes of the first corner portion 62, the second corner portion 65, and the third corner portion 68 are the same as those in the above embodiment.
[0054]
As a result, when the first corner portion 62 is located at point A, the dispersibility and penetration force of the spray during stratified combustion was suppressed, but the dispersibility and penetration force required during homogeneous combustion could not be obtained. . Moreover, when the 1st corner | angular part 62 was located in C point, the spray disperse | distributed a little at the time of stratified combustion. In addition, the spray was dispersed to some extent during homogeneous combustion, but did not become an ideal conical shape.
[0055]
Further, when the first corner portion 62 is located at the point D, the dispersibility of the spray during stratified combustion is hardly suppressed, which is insufficient to achieve the object of the present invention. Moreover, when the 1st corner | angular part 62 is located in E point, the dispersibility of the spray at the time of stratified combustion is not suppressed at all, and the objective of this invention was not achieved.
[0056]
【The invention's effect】
As described above, the fuel injection nozzle of the present invention directly injects a spray of gasoline into the combustion chamber at the time of stratified combustion in a direct injection type gasoline engine. The injected spray of gasoline collides with a collision portion formed in a part of the hollow hole of the sleeve. The spray is reflected radially inward and downstream at the impingement part, thereby suppressing dispersibility. In addition, a part of the kinetic energy is lost at the time of collision with the collision part, and the penetration force is suppressed. Gasoline spray with reduced dispersibility and penetration forces ensures that the gasoline engine in the stratified combustion mode generates moderate and low power.
[Brief description of the drawings]
FIG. 1 is a longitudinal cross-sectional explanatory view (left half omitted) showing a first embodiment of a fuel injection nozzle of the present invention.
FIGS. 2A, 2B, 2C, and 2D are explanatory views showing a modified example of a collision portion.
FIGS. 3A and 3B are explanatory views showing a modified example of a collision portion. FIGS.
4A and 4B are explanatory views showing spray patterns. FIG.
FIGS. 5A and 5B are explanatory views showing spray patterns. FIGS.
FIGS. 6A and 6B are explanatory views showing a modification of the spray pattern. FIGS.
FIG. 7 is a longitudinal cross-sectional explanatory view (left half is omitted) showing a second embodiment of the fuel injection nozzle of the present invention.
FIGS. 8A and 8B are explanatory views showing a sleeve having a plurality of collision portions. FIG.
FIG. 9 is a longitudinal sectional view of an essential part showing an embodiment of the present invention.
FIG. 10 is an explanatory view showing a spray pattern at the time of homogeneous combustion in the embodiment.
FIGS. 11A and 11B are explanatory views showing spray patterns at the time of stratified combustion in the embodiment.
FIGS. 12A, 12B, and 12C are explanatory diagrams showing a relationship between a time during homogeneous combustion and a spray pattern in the embodiment.
FIGS. 13A, 13B, and 13C are explanatory views showing the relationship between the time during stratified combustion and the spray pattern in the embodiment.
FIG. 14 is an explanatory view showing homogeneous combustion of a general direct injection gasoline engine.
FIG. 15 is an explanatory diagram showing stratified combustion of a general direct injection gasoline engine.
FIG. 16 is a longitudinal sectional view showing an example of a conventional fuel injection nozzle.
[Explanation of symbols]
10: Injection hole plate 12: Injection hole
16: Hollow hole 17: Inner peripheral wall
20: Collision part 21: Corner part
l: Extension line 110: Nozzle body
115: Needle valve

Claims (6)

A nozzle body in which an annular valve seat is formed on the inner peripheral wall surface defining the nozzle hole;
An annular valve portion is formed on the outer peripheral wall surface facing the inner peripheral wall surface, and the valve portion is separated from and seated on the valve seat by being moved in the axial direction;
A collision part that is attached to the nozzle body and collides with an inner peripheral wall surface located downstream of a plurality of injection holes facing the nozzle holes, with gasoline spray directly injected from the injection holes into a combustion chamber during stratified combustion A fuel injection nozzle comprising:
A fuel injection nozzle characterized in that the spray of gasoline does not collide with the collision part when being injected into a combustion chamber during homogeneous combustion. 2. The fuel injection nozzle according to claim 1, wherein the collision portion is located 2 to 5 degrees upstream of an extension line of the axis of the nozzle hole, and a small amount of spray collides with the collision portion during stratified combustion . 3. The fuel injection nozzle according to claim 2, wherein a plurality of the collision portions having different inner diameters and separated in the upstream and downstream directions are aligned on an extension line of the axis of the injection hole. The fuel injection nozzle according to claim 3 , wherein each of the collision portions includes an annular corner portion. The fuel injection nozzle according to claim 1, wherein the injection hole is formed in an injection hole plate attached to the nozzle body. The fuel injection nozzle according to claim 5 , wherein a ratio t / d between a thickness t of the nozzle hole plate and a hole diameter d of the nozzle hole is 0.5 to 2.0.

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