JP2006046265A - Fuel injection apparatus of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection apparatus of an internal combustion engine which suppresses the generation of smoke. <P>SOLUTION: A main fuel injection valve 10 and a sub fuel injection valve 11 are arranged on an inner wall surface of a cylinder head on a symmetry plane K-K which extends passing the central axial line of a cylinder. On a projection plane P substantially perpendicular to the central axial line of the cylinder, axial lines Ha-Hh of injection holes of the main fuel injection valve 10 extend outward in the radial direction from the main fuel injection valve 10 and intersect an inner wall surface 5a of a concave groove so as to form main fuel collision points Ga-Gh. Axial lines Ja, Jb of injection holes of the sub fuel injection valve 11 intersect the inner wall surface 5a of the concave groove so as to form sub fuel collision points Fa, Fb. In this case, the axial lines Ja, Jb of the injection holes of the sub fuel injection valve 11 are so oriented as not to pass the central portion of the concave groove 5. Further, the axial lines Ja, Jb of the injection holes of the sub fuel injection valve 11 are oriented so that the sub fuel collision point Fa is located upstream of the main fuel collision point Ga with respect to a swirling flow S and that the sub fuel collision point Fb is located upstream of the main fuel collision point Gf with respect to the swirling flow S. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel injection device for an internal combustion engine.

  A main fuel injection valve is arranged at the center of the inner wall surface of the cylinder head, and a sub fuel injection valve is arranged on the inner wall surface of the cylinder head around the main fuel injection valve. There is known an internal combustion engine in which fuel is injected from a main fuel injection valve and a sub fuel injection valve into a concave groove formed on the top surface of a piston in the presence (see Patent Documents 1 and 2). In the internal combustion engines described in Patent Documents 1 and 2, the injection hole axis of the auxiliary fuel injection valve is oriented so that the fuel spray from the auxiliary fuel injection valve crosses the cylinder central axis.

JP-A-9-317604 Japanese Patent Laid-Open No. 7-71347 JP-A-8-246935 Japanese Patent Laid-Open No. 7-238877

  By the way, when a swirl flow is formed in the cylinder or in the groove and combustion is started in the presence of the swirl flow, relatively heavy oxygen moves to the peripheral edge of the groove due to the centrifugal force of the swirl flow and is relatively light. Burnt gas moves to the center of the groove. As a result, oxygen deficiency occurs at the center of the groove.

  On the other hand, even if fuel is injected from the fuel injection valve toward the inner wall surface of the groove, not all fuel reaches the inner wall surface of the groove. Some of the fuel loses speed during the flight, and may remain at an intermediate position between the fuel injection valve and the inner wall surface of the groove. Then, when the fuel spray from the auxiliary fuel injection valve crosses the cylinder center axis as in the above-described internal combustion engine, a part of the fuel stays at the center of the groove.

  However, as described above, oxygen deficiency occurs at the center of the groove. For this reason, there is a problem that a large amount of smoke may occur in the internal combustion engine described above.

  Therefore, an object of the present invention is to provide a fuel injection device for an internal combustion engine that can suppress the generation of smoke.

  In order to solve the above-mentioned problem, according to the first invention, the main fuel injection valve is arranged at the center of the inner wall surface of the cylinder head, and the auxiliary fuel injection valve is arranged on the inner wall surface of the cylinder head around the main fuel injection valve. An internal combustion engine in which fuel is injected from the main fuel injection valve and the sub fuel injection valve into a concave groove formed in the top surface of the piston in the presence of a swirling flow around the cylinder center axis formed in the cylinder. In a fuel injection device for an engine, the auxiliary fuel injection valve has a plurality of injection holes, and directs each injection hole axis of the auxiliary fuel injection valve so that fuel spray from the auxiliary fuel injection valve does not cross the cylinder central axis. Yes.

  According to the second invention, in the first invention, the main fuel injection valve has a plurality of injection holes, and the injection holes of the main fuel injection valve are on a projection plane substantially perpendicular to the cylinder center axis. A sub-fuel injection axis is obtained by intersecting the inner axis of the sub-fuel injection valve between the two main fuel collision points adjacent to each other among the main fuel collision points obtained by intersecting the inner wall with the inner surface of the groove. Each nozzle hole axis of the auxiliary fuel injection valve is oriented so that the fuel collision point is located.

  According to the third invention, in the first or second invention, the main fuel injection is performed by the main fuel injection valve near the compression top dead center, and the pilot injection is performed by the sub fuel injection valve prior to the main fuel injection. The sub fuel injection is performed upstream of the swirl flow at the main fuel collision point obtained by intersecting the nozzle hole axis of the main fuel injection valve with the inner wall surface of the groove on the projection plane substantially perpendicular to the cylinder center axis. Each nozzle hole axis of the auxiliary fuel injection valve is oriented so that the auxiliary fuel collision point obtained by intersecting the nozzle hole axis of the valve with the inner wall surface of the groove is located.

  According to a fourth invention, in the third invention, on the projection surface, the cylinder head inner wall surface located downstream with respect to the swirling flow at the auxiliary fuel collision point and upstream with respect to the swirling flow at the main fuel collision point, A glow plug is placed.

  Further, according to the fifth aspect, in any one of the first to fourth aspects, the sub fuel injection valve is disposed so as to be inclined with respect to the main fuel injection valve so as to approach each other as it approaches the tip. Directing the axis of each injection hole of the auxiliary fuel injection valve so that fuel is injected into the groove on the side of the main fuel injection valve and fuel is not injected into the groove on the side opposite to the main fuel injection valve. I am letting.

  According to the sixth invention, in any one of the first to fifth inventions, the distance from the auxiliary fuel injection valve to the inner wall surface of the groove along the nozzle hole axis is the main axis along the nozzle hole axis. Each nozzle hole axis of the auxiliary fuel injection valve is oriented so as to be substantially equal to the distance from the fuel injection valve to the inner wall surface of the groove.

  According to a seventh aspect, in any one of the first to sixth aspects, the auxiliary fuel injection valve has at least first and second injection holes, and is projected substantially perpendicular to the cylinder center axis. On the surface, the angle formed between the axis of the first nozzle hole and the flow direction of the swirl flow is an acute angle, and the angle formed between the axis of the second nozzle hole and the flow direction of the swirl flow is obtuse The axis of each injection hole of the auxiliary fuel injection valve is directed.

  According to the eighth invention, in the seventh invention, the diameter of the second nozzle hole is set larger than the diameter of the first nozzle hole.

  According to the ninth aspect, in the seventh aspect, the distance from the auxiliary fuel injection valve along the axis of the second injection hole to the inner wall surface of the groove is the auxiliary value along the axis of the first injection hole. Each nozzle hole axis of the auxiliary fuel injection valve is oriented so as to be longer than the distance from the fuel injection valve to the inner wall surface of the groove.

  According to the tenth invention, in the seventh invention, the angle formed by the axis of the first nozzle hole and the axis of the second nozzle hole is bisected on the projection plane substantially perpendicular to the cylinder center axis. Each nozzle hole axis of the auxiliary fuel injection valve is oriented so that the angle formed by the straight line and the flow direction of the swirl flow is an obtuse angle.

  According to the eleventh invention, in any one of the first to tenth inventions, the maximum spray angle of the auxiliary fuel injection valve is set smaller than the maximum spray angle of the main fuel injection valve.

  According to the twelfth invention, in any one of the first to eleventh inventions, the fuel injection pressure in the auxiliary fuel injection valve is set higher than the fuel injection pressure in the main fuel injection valve.

  According to a thirteenth aspect of the invention, in any one of the first to twelfth aspects of the invention, the injection hole length / diameter ratio of the auxiliary fuel injection valve is set to the injection hole length / diameter ratio of the main fuel injection valve. Is set smaller.

  According to the fourteenth invention, in any one of the first to thirteenth inventions, the auxiliary fuel injection valve is arranged on the inner wall surface of the cylinder head closer to the intake valve than to the exhaust valve. ing.

  The occurrence of smoke can be suppressed.

  1 to 3 show a case where the present invention is applied to a compression ignition type internal combustion engine. The present invention can also be applied to a spark ignition internal combustion engine.

  Referring to FIGS. 1 to 3, for example, 1 is an engine body having four cylinders, 2 is a cylinder block, 2a is a cylinder bore inner wall surface, 3 is a cylinder head, 3a is a cylinder head inner wall surface, 4 is a piston, Combustion chamber formed of a concave groove formed on the top surface of the piston 4, 5a is an inner wall surface of the concave groove, 6a and 6b are a pair of intake ports formed in the cylinder head 3, 7a and 7b are a pair of intake valves, 8a 8b are a pair of exhaust ports formed in the cylinder head 3, and 9a, 9b are a pair of exhaust valves. The intake ports 6a and 6b are connected to a surge tank (not shown) via an intake branch pipe (not shown). On the other hand, the exhaust ports 8a and 8b are connected to an exhaust manifold (not shown).

  In particular, as shown in FIGS. 2 and 3, the intake port 6a and the intake valve 7a and the intake port 6b and the intake valve 7b are arranged substantially symmetrically with respect to a plane of symmetry KK extending through the cylinder center axis LL. The exhaust port 8a and the exhaust valve 9a, the exhaust port 8b and the exhaust valve 9b are also arranged substantially symmetrically with respect to the symmetry plane KK. The center of the combustion chamber 5 is substantially coincident with the cylinder center axis LL.

  A main fuel injection valve 10 is disposed almost at the center of the cylinder head inner wall surface 3 a so as to face the center of the combustion chamber 5. A sub fuel injection valve 11 is arranged on the cylinder head inner wall surface 3 a around the main fuel injection valve 10. Specifically, the main fuel injection valve 10 and the sub fuel injection valve 11 are arranged so that the respective tips are located on the symmetry plane KK.

  In this case, as can be seen from FIGS. 1 and 3, the auxiliary fuel injection valve 11 is arranged with respect to the main fuel injection valve 10 offset from the exhaust valves 9 a, 9 b side to the intake valves 7 a, 7 b side. In this way, it is possible to prevent the auxiliary fuel injection valve 11 from being heated by the exhaust gas flowing through the exhaust ports 8a and 8b. Further, the auxiliary fuel injection valve 11 is disposed approximately in the middle between the main fuel injection valve 10 and the groove inner wall surface 5a.

  In particular, as shown in FIG. 1, the main fuel injection valve 10 is arranged such that its central axis substantially coincides with the cylinder central axis LL. On the other hand, the auxiliary fuel injection valves 11 are arranged such that the central axis MM thereof is inclined with respect to the central axis LL of the main fuel injection valve 10, or the main fuel injection valves 10 are brought closer to each other toward the tip. It is inclined with respect to.

  In the example shown in FIG. 1, the main fuel injection valve 10 and the sub fuel injection valve 11 are connected to a common fuel reservoir, that is, a common rail 12 via corresponding fuel supply pipes 10a and 11a, respectively, and the common rail 12 controls the discharge amount. Connected to possible fuel pump 13. A fuel sensor 14 for detecting the fuel pressure in the common rail 12 is attached to the common rail 12, and the discharge amount of the fuel pump 13 is controlled so that the fuel pressure matches the target fuel pressure. Therefore, in the example shown in FIG. 1, the injection pressures of the main fuel injection valve 10 and the sub fuel injection valve 11 are equal to each other.

  As shown in FIG. 3, a swirl control valve 15 is disposed in the intake port 6a. When the swirl control valve 15 is closed, the intake gas flows into the cylinder only from the intake port 6b. As a result, as shown in FIG. 3, the intake gas flows around the cylinder center axis LL into the cylinder and the combustion chamber 5. A swirling flow S is formed. On the other hand, when the swirl control valve 15 is opened, a large amount of intake gas flows into the cylinder through both intake ports 6a and 6b.

  In the internal combustion engine shown in FIG. 1, main fuel injection is performed by the main fuel injection valve 10 near the compression top dead center (TDC), and pilot injection is performed by the sub fuel injection valve 11 prior to main fuel injection. That is, as shown in FIG. 4A, the main fuel Qm is injected from the main fuel injection valve 10 into the concave groove 5 in the vicinity of the compression TDC. As shown in FIG. 4B, the auxiliary fuel Qp is injected into the recessed groove 5 from the auxiliary fuel injection valve 11 earlier than the main fuel injection by the crank angle interval INT. In this case, the crank angle interval INT is set to about 5 °.

  As shown in FIG. 4C, the crank angle interval INT can be set to about 30 ° from 20 before compression top dead center (BTDC). Alternatively, as shown in FIG. 4D, the auxiliary fuels Qp1 and Qp2 can be injected in a plurality of times. In this case, the injection timing of the preceding auxiliary fuel Qp1 can be set in the same manner as in FIG. 4C, and the injection timing of the subsequent auxiliary fuel Qp2 is set in the same manner as in FIG. 4B. Can do. Further, additional fuel can be injected from the auxiliary fuel injection valve 11 in the expansion stroke or the exhaust stroke after the main fuel injection is performed. In any case, the number of fuel injections performed by the sub fuel injection valve 11 is preferably equal to or greater than the number of fuel injections performed by the main fuel injection valve 10.

  Next, referring to FIG. 5 showing the tip of the auxiliary fuel injection valve 11, 20 is a casing, 21 is a needle that can slide in the casing 20 in the direction of the axis MM, 22 is a valve seat, and 23 is a sack portion. 24a and 24b are a pair of injection holes extending from the sack portion 23, and Ja and Jb are injection hole axes that are the central axes of the injection holes 24a and 24b, respectively. When the needle 21 is seated on the valve seat 22, no fuel is injected. When the needle 21 is disengaged from the valve seat 22, the fuel reaches the sac portion 23 and is then injected from the injection holes 24a and 24b.

  The main fuel injection valve 10 is configured similarly to the sub fuel injection valve 11. However, the number of injection holes of the main fuel injection valve 10 is eight, for example. Note that the number of nozzle holes of the main fuel injection valve 10 may be ten, for example, and the number of nozzle holes of the auxiliary fuel injection valve 11 may be four, for example.

  FIG. 6 shows the injection hole axes Ha, Hb, Hc, Hd, He, Hf, Hg, Hh and the auxiliary fuel injection valves of the main fuel injection valve 10 projected on the projection plane P substantially perpendicular to the cylinder center axis LL. 11 nozzle hole axes Ja and Jb are shown. As shown in FIG. 6, the nozzle hole axis Ha-Hh of the main fuel injection valve 10 extends radially outward from the main fuel injection valve 10 in the radial direction at substantially equal intervals, and intersects the inner wall surface 5a of the groove. Main fuel collision points Ga, Gb, Gc, Gd, Ge, Gf, Gg, Gh are formed, respectively.

  Similarly, the nozzle hole axes Ja and Jb of the auxiliary fuel injection valve 11 also extend outward in the radial direction from the auxiliary fuel injection valve 11 and intersect the concave groove inner wall surface 5a to form auxiliary fuel collision points Fa and Fb, respectively.

  In this case, the injection hole axis lines Ja and Jb of the auxiliary fuel injection valve 11 are directed so as not to pass through the central portion of the concave groove 5. In other words, the injection hole axes Ja and Jb of the auxiliary fuel injection valve 11 are directed so that the fuel spray from the auxiliary fuel injection valve 11 does not cross the cylinder center axis LL.

  Further, the sub fuel collision point Fa is positioned between the two main fuel collision points Gh and Ga adjacent to each other, and the sub fuel collision point Fb is positioned between the two main fuel collision points Ge and Gf adjacent to each other. The injection hole axis lines Ja and Jb of the auxiliary fuel injection valve 10 are directed. In other words, the secondary fuel injection is performed such that the secondary fuel collision point Fa is located upstream with respect to the swirling flow S at the main fuel collision point Ga and the secondary fuel collision point Fb is located upstream with respect to the swirling flow S at the main fuel collision point Gf. The nozzle hole axes Ja and Jb of the valve 11 are directed.

  The fuel travels along the injection hole axis from the main fuel injection valve 10 and the sub fuel injection valve 11 and reaches the vicinity of the corresponding collision point. However, the fuel loses its speed while traveling, and therefore does not necessarily collide with the groove inner wall surface 5a at the collision point.

  Now, when pilot injection is performed from the auxiliary fuel injection valve 11, the fuel advances along the nozzle hole axes Ja and Jb, and as a result, fuel sprays Xa and Xb are formed as shown in FIG. . These fuel sprays Xa and Xb are caused to flow by the swirl flow S, and as shown in FIG. 7 (B), the fuel spray Xa travels on the injection hole axis Ha of the main fuel injection valve 10 or near the main fuel collision point Ga. The fuel spray Xb proceeds on the injection hole axis Hf of the main fuel injection valve 10 or near the main fuel collision point Gf.

  Next, when the main fuel injection is performed from the main fuel injection valve 10, the fuel advances along the injection hole axis Ha-Hh, and as a result, as shown in FIG. Ya, Yb, Yc, Yd, Ye, Yf, Yg, Yh are formed.

  At this time, the fuel sprays Xa and Xb have been ignited immediately before or already. Therefore, the main fuel Qm (FIG. 4) can be reliably ignited and burned, and thus the generation of smoke can be reliably suppressed.

  Further, as described above, the injection hole axes Ja and Jb of the auxiliary fuel injection valve 11 are directed so that the fuel sprays Xa and Xb from the auxiliary fuel injection valve 11 do not cross the cylinder center axis LL. As a result, the fuel injected from the auxiliary fuel injection valve 11 is prevented from staying in the central portion of the concave groove 5 where oxygen deficiency may occur, and therefore the generation of smoke can be reliably suppressed.

  By the way, in the fuel injection valve having a plurality of injection holes, when the maximum angle formed by the injection hole axis is referred to as the maximum spray angle, the angle α shown in FIG. 5 represents the maximum spray angle of the auxiliary fuel injection valve 11. The angle β indicates the maximum spray angle of the main fuel injection valve 10.

  In the embodiment according to the present invention, as can be seen from FIG. 5, the maximum spray angle α of the auxiliary fuel injection valve 11 is set smaller than the maximum spray angle β of the main fuel injection valve 10. That is, at the crank angle at which pilot injection is performed, the distance from the auxiliary fuel injection valve 11 to the combustion chamber 5 is relatively large, and even in such a case, fuel is reliably injected into the concave groove 5. The maximum spray angle α of the auxiliary fuel injection valve 11 is set.

  Further, in the embodiment according to the present invention, as can be seen from FIG. The injection hole axes Ja and Jb of the auxiliary fuel injection valve 11 are directed so that fuel is not injected into the groove 5r. If it does in this way, the volume of the sack part 23 (FIG. 5) can be reduced.

  Further, in the embodiment according to the present invention, the distance from the auxiliary fuel injection valve 11 along the nozzle hole axes Ja and Jb to the inner surface 5a of the concave groove is recessed from the main fuel injection valve 10 along the nozzle hole axis Ha-Hh. The injection hole axes Ja and Jb of the auxiliary fuel injection valve 11 are oriented so as to be substantially equal to the distance to the groove inner wall surface 5a. In this way, the behavior of the fuel injected from the auxiliary fuel injection valve 11 can be considered to be almost the same as the behavior of the fuel injected from the main fuel injection valve 10.

  By the way, in the embodiment according to the present invention, as shown in FIG. 9, the angle θa formed by the nozzle hole axis Ja and the flow direction T of the swirl flow S is an acute angle, and the second nozzle hole axis Jb and the swirl flow The injection hole axes Ja and Jb of the auxiliary fuel injection valve 11 are oriented so that the angle θb formed with the flow direction T of S is an obtuse angle. From another viewpoint, the injection hole of the auxiliary fuel injection valve 11 has the injection hole axis Ja extending on one side Ku of the symmetry plane KK and the injection hole axis Jb extending on the other side Kd of the symmetry plane KK. This also means that the axes Ja and Jb are directed. In this way, the fuel sprays Xa and Xb can be widely dispersed in the groove 5.

  In this case, the fuel spray Xa (see FIG. 7) formed along the nozzle hole axis Ja has a relatively small incident angle with respect to the inner wall surface 5a of the groove, but is formed along the nozzle hole axis Jb. The incident angle of the fuel spray Xb with respect to the inner surface 5a of the groove is relatively large. This is because the fuel spray Xa that has reached the inner surface 5a of the groove is relatively easy to detach from the inner wall surface 5a of the groove, but the fuel spray Xb that has reached the inner surface 5a of the groove is relatively detached from the inner surface 5a of the groove. It means that it is difficult to do. However, as the amount of fuel adhering to the concave groove inner wall surface 5a increases, the amount of unburned hydrocarbons in the exhaust gas also increases.

  Therefore, it is preferable that the penetration force of the fuel spray Xb is smaller than the penetration force of the fuel spray Xa so that the fuel spray Xb does not easily adhere to the inner surface 5a of the groove.

  In order to achieve this, for example, as shown in FIG. 10, the diameter of the injection hole 24b corresponding to the injection hole axis Jb can be set larger than the diameter of the injection hole 24a corresponding to the injection hole axis Ja. .

  Alternatively, as shown in FIGS. 11A and 11B, the distance from the auxiliary fuel injection valve 11 along the nozzle hole axis Jb to the inner surface 5a of the groove is the auxiliary fuel injection along the nozzle hole axis Ja. The injection hole axis lines Ja and Jb of the auxiliary fuel injection valve 11 can be oriented so as to be longer than the distance from the valve 11 to the groove inner wall surface 5a. Here, in the example shown in FIG. 11A, the auxiliary fuel injection valve 11 is disposed on the symmetry plane KK. In contrast, in the example shown in FIG. 11B, the auxiliary fuel injection valve 11 is disposed on one side Ku of the symmetry plane KK.

  Further, more simply, as shown in FIGS. 12A and 12B, the angles θa and θb described above may be reduced to reduce the incident angle of the fuel sprays Xa and Xb with respect to the concave groove inner wall surface 5a. it can. That is, in the example shown in FIG. 12A, the straight line W that bisects the angle αP formed by the nozzle hole axis Ja and the nozzle hole axis Jb on the projection plane P and the flow direction T of the swirling flow S are formed. The injection hole axis lines Ja and Jb of the auxiliary fuel injection valve 11 are oriented so that the angle φ is an obtuse angle. On the other hand, in the example shown in FIG. 12B, the injection hole axes Ja, Jb of the auxiliary fuel injection valve 11 are directed so that the injection hole axes Ja, Jb extend only on one side of the symmetry plane KK. . In this case, the angles θa and θb formed by the nozzle hole axes Ja and Jb and the flow direction T of the swirling flow S are both acute angles, so that the incident angle of the fuel sprays Xa and Xb with respect to the inner surface 5a of the groove is reduced.

  FIG. 13 shows an example of the arrangement of the glow plug 30 when the injection hole axis lines of the main fuel injection valve 10 and the auxiliary fuel injection valve 11 are oriented as shown in FIG. Referring to FIG. 13, on the projection plane P, the glow plug 30 is formed on the cylinder head inner wall surface 3 a located downstream with respect to the swirling flow S at the auxiliary fuel collision point Fa and upstream with respect to the swirling flow S at the main fuel collision point Ha. Be placed. In this way, the fuel spray Xa from the auxiliary fuel injection valve 11 contacts the glow plug 30 while being moved by the swirl flow S (see FIGS. 7 and 8). Therefore, the fuel spray Xa can be reliably ignited, and the engine can be started reliably and promptly. Further, the progress or diffusion of the fuel spray from the main fuel injection valve 10 is not hindered by the glow plug 30.

  By the way, in the pilot injection performed by the auxiliary fuel injection valve 11, it is necessary to inject a considerably smaller amount of fuel than the main fuel injection. Therefore, the auxiliary fuel injection valve 11 can be configured so that the flow rate at the nozzle hole of the auxiliary fuel injection valve 11 is, for example, half the flow rate at the nozzle hole of the main fuel injection valve 10.

  Further, in order to widely disperse the fuel injected from the auxiliary fuel injection valve 11, the length-to-diameter ratio of the injection hole of the auxiliary fuel injection valve 11 is set to be larger than the length-to-diameter ratio of the injection hole of the main fuel injection valve 10. It can also be set small.

  Alternatively, the fuel injection pressure in the auxiliary fuel injection valve 11 can be set higher than the fuel injection pressure in the main fuel injection valve 10 in order to promote atomization of the fuel injected from the auxiliary fuel injection valve 11. Specifically, as shown in FIG. 14, the main fuel injection valve 10 and the sub fuel injection valve 11 are connected to corresponding common rails 40 and 41 via fuel supply pipes 10a and 11a, respectively. The auxiliary fuel injection valve common rail 41 is connected to the fuel pump 13 on the one hand, and connected to the main fuel injection valve common rail 40 via the electromagnetic valve 42 on the other hand. The main fuel injection valve common rail 40 is connected to the fuel tank 13 via an electromagnetic valve 43 and a return passage 44. Further, fuel pressure sensors 45 and 46 for detecting the fuel pressure inside the common rails 40 and 41 are attached.

  In this case, the discharge amount of the fuel pump 13 is controlled so that the fuel pressure in the sub-fuel injection valve common rail 41 becomes a relatively high target fuel pressure. Further, the solenoid valves 42 and 43 are controlled to be opened and closed so that the fuel pressure in the main fuel injection valve common rail 40 becomes a relatively low target fuel pressure.

  Furthermore, in order to promote atomization of fuel from the auxiliary fuel injection valve 11, for example, an electric heater 47 may be attached to the fuel supply pipe 11a to heat the fuel injected from the auxiliary fuel injection valve 11.

It is a longitudinal cross-sectional view of an internal combustion engine. It is a bottom view of a cylinder head. It is a top view of a piston. It is a time chart for demonstrating main fuel injection and pilot injection. It is a partial expanded sectional view of an auxiliary fuel injection valve. It is a projection view for demonstrating the directivity direction of a nozzle hole axis line of the Example by this invention. It is a projection for demonstrating the Example by this invention. It is a projection for demonstrating the Example by this invention. It is a projection view for explaining angles θa and θb. It is a partial expanded sectional view of the auxiliary fuel injection valve of another Example by this invention. It is a projection view for demonstrating the directivity direction of a nozzle hole axis of another Example by this invention. It is a projection view for demonstrating the directivity direction of a nozzle hole axis line of the Example by this invention. It is a projection view which shows arrangement | positioning of a glow plug. It is a figure which shows another Example by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine main body 3a Cylinder head inner wall surface 5 Concave groove 10 Main fuel injection valve 11 Sub fuel injection valve Ja, Jb Injection hole axis line of auxiliary fuel injection valve K Symmetry surface L Cylinder center axis S Swirling flow

Claims (14)

  A main fuel injection valve is arranged at substantially the center of the inner wall surface of the cylinder head, and a sub fuel injection valve is arranged on the inner wall surface of the cylinder head around the main fuel injection valve. In the fuel injection device for an internal combustion engine in which fuel is injected from a main fuel injection valve and a sub fuel injection valve into a concave groove formed on the top surface of the piston, the sub fuel injection valve has a plurality of injections. A fuel injection device for an internal combustion engine having a hole and directing each nozzle hole axis of the auxiliary fuel injection valve so that fuel spray from the auxiliary fuel injection valve does not cross the cylinder central axis.   The main fuel injection valve has a plurality of injection holes, and the main fuel collision obtained by intersecting the injection hole axis line of the main fuel injection valve with the inner wall surface of the groove on the projection plane substantially perpendicular to the cylinder center axis line Each of the sub fuel injection valves is positioned so that the sub fuel collision point obtained by intersecting the nozzle axis of the sub fuel injection valve with the inner wall surface of the concave groove is positioned between two main fuel collision points adjacent to each other. The fuel injection device for an internal combustion engine according to claim 1, wherein the injection hole axis is directed.   The main fuel injection is performed by the main fuel injection valve in the vicinity of the compression top dead center, and the pilot injection is performed by the auxiliary fuel injection valve prior to the main fuel injection, and the main fuel injection is performed on the projection plane substantially perpendicular to the cylinder center axis. The auxiliary fuel obtained by crossing the nozzle hole axis of the auxiliary fuel injection valve with the inner wall surface of the concave groove upstream of the swirl flow of the main fuel collision point obtained by intersecting the nozzle hole axis of the fuel injection valve with the inner wall surface of the concave groove The fuel injection device for an internal combustion engine according to claim 1 or 2, wherein each nozzle hole axis of the auxiliary fuel injection valve is directed so that the collision point is located.   4. The fuel for an internal combustion engine according to claim 3, wherein a glow plug is disposed on the inner wall surface of the cylinder head located downstream of the swirl flow at the sub fuel collision point and upstream of the swirl flow of the main fuel collision point on the projection plane. Injection device.   The auxiliary fuel injection valves are arranged to be inclined with respect to the main fuel injection valve so as to approach each other as they approach the front end, and fuel is injected into the concave groove on the main fuel injection valve side with respect to the auxiliary fuel injection valve, and the main fuel injection valve The fuel injection device for an internal combustion engine according to any one of claims 1 to 4, wherein each nozzle hole axis of the auxiliary fuel injection valve is directed so that fuel is not injected into the concave groove on the opposite side to the first.   The distance from the auxiliary fuel injection valve along the nozzle hole axis to the inner wall surface of the groove is substantially equal to the distance from the main fuel injection valve along the nozzle hole axis to the inner wall surface of the groove. The fuel injection device for an internal combustion engine according to any one of claims 1 to 5, wherein each nozzle hole axis is directed.   The auxiliary fuel injection valve has at least first and second injection holes, and an angle formed by the axis of the first injection hole and the flow direction of the swirl flow is an acute angle on a projection plane substantially perpendicular to the cylinder center axis. And each nozzle hole axis of the auxiliary fuel injection valve is oriented so that an angle formed between the axis of the second nozzle hole and the flow direction of the swirl flow is an obtuse angle. The fuel injection device for an internal combustion engine according to one item.   The fuel injection device for an internal combustion engine according to claim 7, wherein the diameter of the second nozzle hole is set larger than the diameter of the first nozzle hole.   The distance from the auxiliary fuel injection valve to the inner wall surface of the groove along the axis of the second injection hole is longer than the distance from the auxiliary fuel injection valve to the inner wall surface of the groove along the axis of the first injection hole. The fuel injection device for an internal combustion engine according to claim 7, wherein each injection hole axis of the auxiliary fuel injection valve is oriented as described above.   On the projection plane substantially perpendicular to the cylinder center axis, the angle formed by the straight line that bisects the angle between the axis of the first nozzle hole and the axis of the second nozzle and the flow direction of the swirl flow is obtuse. 8. The fuel injection device for an internal combustion engine according to claim 7, wherein each nozzle hole axis of the auxiliary fuel injection valve is directed.   The fuel injection device for an internal combustion engine according to any one of claims 1 to 10, wherein the maximum spray angle of the auxiliary fuel injection valve is set smaller than the maximum spray angle of the main fuel injection valve.   The fuel injection device for an internal combustion engine according to any one of claims 1 to 11, wherein a fuel injection pressure in the auxiliary fuel injection valve is set higher than a fuel injection pressure in the main fuel injection valve.   The fuel of the internal combustion engine according to any one of claims 1 to 12, wherein a ratio of the length of the nozzle hole of the auxiliary fuel injection valve to the diameter ratio is set smaller than a ratio of the length of the nozzle hole of the main fuel injection valve to the diameter. Injection device.   The fuel injection device for an internal combustion engine according to any one of claims 1 to 13, wherein a sub fuel injection valve is disposed on the inner wall surface of the cylinder head closer to the intake valve than to the exhaust valve.

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