JP2007231852A - Fuel injection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection device capable of inhibiting deterioration of exhaust emission when fuel injection is changed according to a condition of an internal combustion engine and capable of providing necessary output at a time of heavy load of the internal combustion engine. <P>SOLUTION: In this fuel injection device 1A, a needle valve 20 is arranged in a nozzle body 10 having a first injection hole 13 and a second injection hole 14 formed thereon, and a condition where the second injection hole 14 is opened through a condition where the first injection hole 13 is opened is formed when the needle valve 20 separates from a seated position and moves, and cone angles of the first injection hole is established narrower than cone angles of the second injection hole. Since the cone angles of the first injection hole which opens at first when the needle valve 20 separates from a seat is established narrower than the cone angles of the second injection hole, in an embodiment, emission of hydrocarbon HC is inhibited and deterioration of exhaust emission can be prevented when the first injection hole opens at a tine of light load of the internal combustion engine. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel injection device used in an internal combustion engine. In particular, the present invention relates to a fuel injection device in which a plurality of types of injection holes having different opening times are formed.

  2. Description of the Related Art In recent years, many studies have been made on techniques for adjusting the injection timing, the injection direction, the spray shape, and the like of fuel injected from an injection hole in accordance with the load state of an internal combustion engine such as a diesel engine or a gasoline engine. If the fuel spray can be changed optimally according to the load state of the internal combustion engine, the air utilization rate can be improved and the fuel consumption can be reduced, and the generation of hydrocarbons (HC), smoke, etc. can be suppressed and exhausted. Emissions can be improved.

  For example, Patent Document 1 discloses a fuel injection device (variable nozzle nozzle) in which two types of nozzle holes, a pilot nozzle hole (first nozzle hole) and a main nozzle hole (second nozzle hole), are provided at different positions of the nozzle body. Is disclosed. This fuel injection device discloses a fuel injection device that drives a needle valve disposed inside up and down to open and close different nozzle holes in order. The pilot injection hole has a wide cone angle for fuel injection so that the injected fuel collides with the fuel injected from the main injection hole provided on the upper side. Further, the pilot nozzle hole has a smaller diameter than the main nozzle hole and is set to have a smaller number. The fuel injected from the pilot injection holes is adjusted to a minimum amount for ignition. This fuel injection device is formed so that a pilot injection hole is first opened when the needle valve is moved upward. When the needle valve is moved further upward, the main nozzle hole arranged so that the central axis intersects the pilot nozzle hole opens.

  In the fuel injection device, atomization is promoted by the collision of the sprayed fuel, and the fuel injected from the pilot nozzle can be ignited. Therefore, the fuel is burned when the needle valve is lifted and the fuel is injected. Can be improved.

Japanese Patent Laid-Open No. 11-173245

  Since the pilot nozzle hole of Patent Document 1 is formed with a small nozzle hole diameter as described above, fuel evaporation can be promoted. However, when the internal combustion engine is in a light load (low load) state, the lift amount of the needle valve is small and only the pilot injection hole is opened. Generally, the in-cylinder temperature is low when the internal combustion engine is in a light load state. In particular, in-cylinder temperature tends to be low in an engine having a low compression ratio. Therefore, if the nozzle hole diameter is small, the air-fuel mixture becomes too lean and the ignitability is reduced. As a result, there is a concern that unburned hydrocarbons (HC) will increase and exhaust emissions will deteriorate.

  In contrast, the increase in HC can be suppressed by narrowing the cone angle of the pilot injection hole. However, in the fuel injection device of Patent Document 1, the fuel injected from the pilot injection hole collides with the fuel injected from the main injection hole. Therefore, the pilot cone has a wide cone angle. Therefore, it is difficult to narrow the cone angle of the pilot nozzle hole. In general, when the cone angle of the nozzle hole is narrowed, there is a concern that smoke will deteriorate when the internal combustion engine is in a high load state, and a decrease in output may be a problem.

  Accordingly, an object of the present invention is to provide a fuel injection device that can suppress deterioration of exhaust emission when fuel injection is changed in accordance with the state of the internal combustion engine, and that can obtain a required output when the internal combustion engine is at a high load. That is.

  The object is to place a needle valve in the nozzle body in which the first nozzle hole and the second nozzle hole are formed, and when the needle valve moves away from the seating position, the first nozzle hole is A fuel injection device capable of forming a state in which the second nozzle hole is also opened through an open state, wherein a cone angle of the first nozzle hole is set narrower than a cone angle of the second nozzle hole. This is achieved by a fuel injection device characterized in that it is.

  According to the present invention, the cone angle of the first nozzle hole that opens first when the needle valve moves away from the seating position is made narrower than the cone angle of the second nozzle hole. Sometimes, when the first nozzle hole is opened, the generation of hydrocarbons (HC) can be suppressed and the exhaust emission can be prevented from deteriorating.

  Moreover, it is good also as a structure where the said 1st nozzle hole is arrange | positioned in the position lower than a said 2nd nozzle hole with the moving direction of the said needle valve. In this case, it is possible to avoid the interference between the fuels injected from the first nozzle hole and the second nozzle hole, and to improve the air utilization rate. Therefore, it is possible to prevent the exhaust emission from deteriorating.

  Moreover, it is good also as a structure where the said 1st injection hole is arrange | positioned in the position higher than a said 2nd injection hole in the moving direction of the said needle valve. In this case, the axis of the first nozzle hole and the axis of the second nozzle hole may be set to intersect each other. By making the axes intersect each other within a certain angle range, the fuel injected from the first nozzle hole and the second nozzle hole is crossed before reaching the combustion chamber wall surface, and atomization and spray penetration force The air utilization rate can be improved by strengthening. Therefore, it is possible to prevent the exhaust emission from deteriorating at the time of high load of the internal combustion engine and obtain a necessary output.

  Further, the first nozzle hole and the second nozzle hole may be formed so as to be shifted by a predetermined angle around the central axis of the nozzle body. If the nozzle holes are shifted by a predetermined angle, the injected fuel can be prevented from interfering and sprayed widely in the circumferential direction, so that the air utilization rate can be improved. And the output required at the time of high load of an internal combustion engine is obtained. The first nozzle hole may be arranged on the downstream side of the second nozzle hole in the swirl forming direction. By setting in this way, it is possible to prevent the air-fuel mixture that has overflowed once after entering the combustion chamber from interfering with the spray in the second injection hole, thereby suppressing the generation of smoke and preventing the exhaust emission from deteriorating. .

  According to the present invention, it is possible to provide a fuel injection device that can suppress deterioration of exhaust emission when fuel injection is changed according to the state of the internal combustion engine, and that can obtain a required output when the internal combustion engine is under a high load.

  Embodiments according to the present invention will be described below with reference to the drawings.

  1A and 1B are enlarged views of a peripheral portion of a nozzle hole of a fuel injection device 1A according to a first embodiment. FIG. 1A is a longitudinal sectional view of the fuel injection device 1A, and FIG. It is the bottom view which showed typically the arrangement | positioning relationship of a nozzle hole. Note that FIG. 1A is a cross-sectional view taken along line AA in FIG. The fuel injection device 1A includes a substantially cylindrical nozzle body 10 having a space inside, and a needle valve 20 housed in the nozzle body 10 and reciprocally disposed along a central axis CT. Including.

  The tip portion side (lower side in FIG. 1) of the nozzle body 10 is formed in a hemispherical shape. Inside thereof, there is provided a sack portion 11 whose inside diameter is formed in a semispherical shape at the throttle end. The needle valve 20 is seated on the inner wall surface 12 slightly upstream from the portion where the sack portion 11 is provided. A certain region of the inner wall surface 12 on which the needle valve 20 is seated is a seat surface 12ST of the nozzle body 10. When the needle valve 20 is seated on the seat surface 12ST, the flow of the fuel FE is stopped, and the fuel injection device 1A is closed. FIG. 1A shows this closed state.

  A plurality of nozzle holes 13 and 14 are provided radially at the tip of the nozzle body 10 where the sack portion 11 is formed, with the central axis CT as the center. These nozzle holes are through passages that penetrate the inside and the outside of the nozzle body 10. In particular, the nozzle body 10 has two types of nozzle holes. That is, a first nozzle hole 13 disposed on the lower side in the direction of the central axis CT and a second nozzle hole 14 disposed above the first nozzle hole 13 are formed.

  As shown in FIG. 1B, the plurality of first injection holes 13 are formed so that the outlet side opening 13HL is positioned at a predetermined interval on a circle centered on the central axis CT. The second nozzle hole 14 is also formed so that the outlet side opening 14HL is positioned at a predetermined interval on a concentric circle centered on the central axis CT. The opening 13HL of the first nozzle hole 13 and the opening 14HL of the second nozzle hole 14 are located on a straight line L passing through the central axis CT. Therefore, in FIG. 1A, the opening 13HL and the opening 14HL are in a vertical positional relationship in the direction of the central axis CT. Such nozzle holes 13 and 14 can be formed, for example, by subjecting the nozzle body 10 to electrical discharge machining or laser machining.

  As an example, FIG. 1 shows a case where ten first nozzle holes 13 and ten second nozzle holes 14 are arranged, but the number of nozzle holes may be increased or decreased as needed. The first nozzle holes 13 and the second nozzle holes 14 are in a new arrangement form different from normal. This point will be described in detail later.

  The needle valve 20 accommodated in the nozzle body 10 is formed in a shape corresponding to the inner wall surface 12 of the nozzle body 10. That is, the needle valve 20 has a shape in which a main body portion 21 of a large-diameter cylindrical body and a tip portion 22 of a small-diameter cylindrical body are connected by an intermediate portion 23 whose outer diameter is gradually reduced and inclined.

  The tip portion 22 is a cylindrical body that is just fitted into the sac portion 11 of the nozzle body 10 and can slide up and down. The intermediate portion 23 is formed with a seat portion 23ST that is seated on the seat surface 12ST on the nozzle body 10 side. A plurality of horizontal holes 24 are formed below the intermediate portion 23 at right angles to the central axis CT. All the horizontal holes 24 are connected to a vertical hole 25 provided downward along the central axis CT. The vertical hole 25 penetrates to the end surface of the tip portion 22. When the needle valve 20 moves upward from the state where the seat portion 23ST is seated on the seat surface 12ST of the slip body 10, a gap is generated between the inner surface 12 of the nozzle body 10. At this time, the fuel FE flows into the sack portion 11 through the horizontal hole 24 and the vertical hole 25.

  The fuel injection device 1A includes a needle moving mechanism (not shown). The position where the needle valve 20 moves upward from the seating position with a small lift amount by this needle moving mechanism to open the opening 13NH inside the first injection hole 13 is referred to as a low lift position. The position where the needle valve 20 moves further upward and opens the opening 14NH inside the second injection hole 14 together with the opening 13NH of the first injection hole 13 is referred to as a high lift position.

  Furthermore, the relationship between the first nozzle hole 13 and the second nozzle hole 14 described above will be described. FIG. 2 is a diagram showing a cone angle relationship that defines the direction of the fuel FE injected from the first injection hole 13 and the second injection hole 14. The cone angle is an angle formed by the axis AL of the nozzle hole. The first nozzle holes 13 and the second nozzle holes 14 are set so that the outlet side faces downward, and are arranged radially with respect to the central axis CT. The plurality of first injection holes 13 are formed so as to concentrate on one point CT1 when the axis AL1 is extended to the central axis CT. Therefore, the axis AL1 is a virtual conical bus, and the cone angle is the apex angle of the cone. Since the apex angle of the cone is thus, it may be referred to as a cone angle (or a holocone angle) in the industry. As shown in FIG. 2, the cone angle of the first nozzle hole 13 is α.

  The same applies to the second injection hole 14, and when the axis AL2 is extended to the central axis CT, the second injection hole 14 is formed so as to be concentrated at one point CT2. The cone angle of the second nozzle hole 14 is β. In this embodiment, the cone angle α of the first nozzle hole 13 is set to be narrower than the cone angle β of the second nozzle hole 14.

  When the needle valve 20 is moved from the seating position to the low lift position in the fuel injection device 1A having the above configuration, a certain gap is formed between the intermediate portion 23 of the needle valve 20 and the inner wall surface 12 of the nozzle body 10. As a result, the fuel FE enters the horizontal hole 24 and flows into the sack portion 11 through the vertical hole 25. At the low lift position, only the first nozzle hole 13 is open. At this time, fuel is injected from the lower side with a narrow cone angle α. For example, when the needle valve 20 is set to the low lift position in response to a light load of the internal combustion engine, the fuel FE is sprayed at a narrow cone angle α, so that an increase in unburned hydrocarbon (HC) can be suppressed. Therefore, the internal combustion engine to which such a fuel injection device 1A is applied can suppress the deterioration of exhaust emission at a light load.

  When the needle valve 20 is moved further upward, the first nozzle hole 13 and the second nozzle hole 14 are also opened. At this time, fuel is also injected from the upper second injection hole 14. Since the cone angle β of the second nozzle hole 14 located on the upper side is larger than the cone angle α of the first nozzle hole 13, spraying is performed even if the nozzle holes 13 and 14 are arranged vertically on the same line. Fuel does not interfere with each other. Therefore, the needle valve 20 is set to a high lift position in response to a high load of the internal combustion engine, the fuel FE is injected from the first injection hole 13 at a narrow cone angle α, and further the angle from the second injection hole 14 is increased. When the fuel FE is injected at a wide cone angle β, the fuel FE spreads efficiently in the combustion chamber. Therefore, the use efficiency of air can be improved and combustion can be improved. In this way, the fuel injection device 1A can obtain a necessary output while suppressing deterioration of exhaust emission even when the internal combustion engine is under a high load.

  FIG. 3 is an enlarged longitudinal sectional view showing a peripheral portion of the injection hole of the fuel injection device 1B according to the second embodiment. FIG. 3 shows a state in which the needle valve 20 is in the low lift position. Further, parts corresponding to those of the fuel injection device 1A of the first embodiment shown in FIG. Description is omitted. The same applies to the embodiments described below.

  In the fuel injection device 1B, the positional relationship between the first injection holes 13 and the second injection holes 14 is reversed up and down as compared with the fuel injection device 1A. The first injection hole 13 of the fuel injection device 1B is formed in the vicinity of the downstream side of the seat surface 12ST of the nozzle body 10.

  In the fuel injection device 1B, since the first injection hole 13 having a narrow cone angle is set on the upper side, the first injection hole 13 and the second injection hole 14 are arranged in the vertical direction as in the case of the first embodiment. AL1 and axis AL2 intersect. Therefore, the fuel FE sprayed from the first nozzle hole 13 and the second nozzle hole enters a collision state on the way. However, if the angle difference between the cone angle of the first nozzle hole 13 and the cone angle of the second nozzle hole 14 is adjusted to be within a predetermined range, the fuel atomized by the spray crossing in front of the wall surface of the combustion chamber. As shown in the figure, it is possible to achieve a spray MFE that is in a merged state and has improved spray penetration. Thereby, the air utilization factor when the first injection hole 13 and the second injection hole 14 are opened can be improved in response to a high load of the internal combustion engine. Therefore, also in the case of the fuel injection device 1B, it is possible to suppress the deterioration of the exhaust emission when the internal combustion engine is lightly loaded, and to obtain the necessary output while suppressing the deterioration of the exhaust emission even when the internal combustion engine is lightly loaded.

(Modification)
FIG. 4 is a view showing a fuel injection device 1C according to a modification of the second embodiment. In this modification, the form of the needle valve is changed. The needle valve 20 of Example 2 has a structure in which a horizontal hole 24 and a vertical hole 25 are provided inside and the fuel FE is introduced into the sac portion at the tip and then flows into the second injection hole 14. However, the needle valve need not have such a structure. The modified needle valve 30 is formed by a base end side outer needle portion 31 and a distal end side inner needle portion 32. When the needle valve 30 is moved up and down, only the first injection hole 13 is opened by the outer shape, A state in which the first nozzle hole 13 and the second nozzle hole 14 are opened can be formed.

  FIG. 4 shows a state when the needle valve 30 is in the high lift position on the left side and the needle valve 30 is in the low lift position on the right side with the boundary line BL as a boundary. The effect similar to that of the fuel injection device 1B can be obtained by the fuel injection device 1C of this modification.

  FIG. 5 is an enlarged view of the peripheral portion of the nozzle hole of the fuel injection device 1D according to the third embodiment. FIG. 5A is a longitudinal sectional view of the fuel injection device 1D, and FIG. It is the bottom view which showed typically the arrangement | positioning relationship of a nozzle hole.

  In the fuel injection device 1D, the first injection hole 13 having a narrow cone angle is set on the upper side, similarly to the fuel injection device 1B of the second embodiment. In the case of the fuel injection device 1B of the second embodiment, the case where the nozzle holes 13 and 14 are positioned vertically in the direction of the central axis CT is shown as an example. In the fuel injection device 1D, as shown in FIG. 5B, the first injection hole 13 and the second injection hole 14 are formed by shifting by a predetermined angle γ around the central axis CT. In other words, the other nozzle hole is twisted (shifted) in the circumferential direction with respect to one nozzle hole.

  In the case of the present Example 2, the fuel sprayed from both the nozzle holes 13 and 14 was brought into contact, thereby improving the atomization of the spray and the penetration force of the spray, thereby improving the air utilization rate. However, in this fuel injection device 1D, the interference of the spray is suppressed by shifting the injection direction of the first injection 13 and the injection direction of the second injection hole, and the air utilization rate is improved by spreading the spray to the circumferential method. Yes. With this configuration as well, it is possible to obtain a necessary output while suppressing deterioration of exhaust emission when both the injection holes 13 and 14 are opened when the internal combustion engine is under a high load.

  6A and 6B are enlarged views of the peripheral portion of the injection hole of the fuel injection device 1E according to the fourth embodiment. FIG. 6A is a longitudinal sectional view of the fuel injection device 1E, and FIG. It is the bottom view which showed typically the arrangement | positioning relationship of a nozzle hole.

  This fuel injection device 1E is the same as the fuel injection device 1D of the third embodiment in that the first injection holes 13 and the second injection holes 14 are formed by shifting by a predetermined angle around the central axis CT. . However, there are certain rules in the direction of shifting. Specifically, the first injection hole 13 for performing fuel injection first is disposed downstream of the second injection hole 14 in the swirl formation direction SW so that swirl (lateral vortex) is likely to occur in the combustion chamber. . Arranged in this way, it is possible to suppress the mixture that has overflowed after entering the combustion chamber from interfering with the spray from the second injection holes 14 that are injected later and fly relatively linearly. This configuration can also improve the air utilization rate and suppress the occurrence of smoke and the like. Therefore, also in the fuel injection device 1E of the fourth embodiment, a necessary output can be obtained while suppressing the deterioration of exhaust emission when both the injection holes 13 and 14 are opened at the time of high load of the internal combustion engine.

  The fuel injection device 1A of the first embodiment described above is a case where the first injection hole 13 with a narrow cone angle is located on the lower side, and in particular, the second injection hole 14 is the first injection hole 13 in the direction of the central axis CT. The case where it has been arrange | positioned on is shown. However, the configuration in which the first nozzle hole 13 is disposed below the second nozzle hole 14 is not limited to the structure of the first embodiment. That is, the first nozzle hole 13 and the second nozzle hole 14 may be formed by shifting a predetermined angle around the central axis. In this case, since the fuel to be sprayed expands in the circumferential direction, it is possible to improve the combustion by improving the air utilization efficiency as in the other embodiments described above. Furthermore, if the first injection hole 13 is arranged downstream of the second injection hole 14 in the swirl formation direction, interference between sprayed fuels can be more reliably suppressed and the generation of a swirl flow can be promoted. The utilization efficiency can be improved.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

It is the figure which expanded and showed the peripheral part of the nozzle hole of 1 A of fuel injection apparatuses which concern on Example 1, (A) is a longitudinal cross-sectional view, (B) is typical about the arrangement | positioning relationship of the nozzle hole formed in the nozzle body. It is a bottom view seen in. It is the figure shown about the relationship of the cone angle which prescribes | regulates the direction of the fuel injected from the 1st nozzle hole and the 2nd nozzle hole. It is the longitudinal cross-sectional view which expanded and showed the peripheral part of the nozzle hole of the fuel-injection apparatus 1B which concerns on Example 2. FIG. It is the figure shown about the fuel-injection apparatus 1C of the modification of Example 2. FIG. It is the figure which expanded and showed the peripheral part of the nozzle hole of fuel injection apparatus 1D which concerns on Example 3, (A) is a longitudinal cross-sectional view, (B) is typical about the arrangement | positioning relationship of the nozzle hole formed in the nozzle body. It is a bottom view seen in. It is the figure which expanded and showed the peripheral part of the nozzle hole of the fuel injection apparatus 1E which concerns on Example 4, (A) longitudinal cross-sectional view, (B) is the arrangement | positioning relationship of the nozzle hole formed in the nozzle body typically It is the shown bottom view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 (AE) Fuel injection apparatus 10 Nozzle body 11 Suck part 12 Inner wall surface 12ST Seat surface 13 1st injection hole 14 2nd injection hole 20, 30 Needle valve 21 Main body part 22 Tip part 23 Intermediate part 23ST Seat part alpha 1st Cone angle of one nozzle hole β Cone angle of second nozzle hole CT Central axis of nozzle body AL1 Axis line of first nozzle hole AL2 Axis line of second nozzle hole FE Fuel SW Swirl formation direction

Claims (6)

A needle valve is arranged in the nozzle body in which the first nozzle hole and the second nozzle hole are formed, and when the needle valve moves away from the seating position, the first nozzle hole is opened. A fuel injection device capable of forming a state in which the second nozzle hole is also opened,
The fuel injection device according to claim 1, wherein a cone angle of the first nozzle hole is set narrower than a cone angle of the second nozzle hole. 2. The fuel injection device according to claim 1, wherein the first injection hole is disposed at a position lower than the second injection hole in a moving direction of the needle valve. 2. The fuel injection device according to claim 1, wherein the first injection hole is disposed at a position higher than the second injection hole in a moving direction of the needle valve. 4. The fuel injection device according to claim 3, wherein the axis of the first nozzle hole and the axis of the second nozzle hole are set to intersect each other. 5. 4. The fuel injection device according to claim 1, wherein the first injection hole and the second injection hole are formed by shifting a predetermined angle around a central axis of the nozzle body. 5. . 6. The fuel injection device according to claim 5, wherein the first injection hole is disposed downstream of the second injection hole in a swirl forming direction.

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