JP2004068726A - Fuel injection device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection device for an internal combustion engine for injecting fuel in a hollow conical form during low load operation of the engine and injecting the fuel in a columnar form with its sufficiently strong penetrating force during high load operation of the engine. <P>SOLUTION: The fuel injection device comprises a first injection hole 5 for fuel injection with no swirl and a second injection hole 6 for fuel injection with swirl. Only the second injection hole 6 is used during the low load operation of the engine for performing fuel injection and only the first injection hole 5 or both the first and second injection holes 5, 6 are used during the high load operation of the engine for performing fuel injection. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel injection device for an internal combustion engine.
[0002]
[Prior art]
Japanese Patent Application Laid-Open No. 2001-12334 discloses that in a fuel injection device, an annular groove is formed so as to overlap an upstream portion of each of the radially formed injection hole inlets, and the amount of fuel is reduced by reducing the lift amount of a valve body. The fuel flows into the injection holes mainly through the annular groove, whereby the fuel is guided to each injection hole as a swirling flow in the annular groove, and the fuel in the swirling flow is injected to form the fuel into a hollow conical shape. It has been proposed to inject.
[0003]
Atomization of the fuel injected in the shape of a hollow cone is promoted, but on the other hand, the penetration force is weakened. Therefore, in order to increase the penetration force of the fuel, the lift amount of the valve body is increased so that the fuel directly flows into the injection hole, and the fuel is injected in a columnar shape without a swirling flow. ing.
[0004]
[Problems to be solved by the invention]
In the above-described fuel injection device, in order to inject the fuel in a hollow conical shape, the injection hole must pass the fuel swirled in the annular groove satisfactorily, and the injection hole diameter is relatively large. Accordingly, even if the fuel is directly injected into the injection hole and the fuel is injected in a columnar shape, the penetration force of the fuel cannot be increased so much. In this way, when a large amount of intake air is supplied into the cylinder and the in-cylinder pressure at the end of the compression stroke is high as in the case of high engine load, fuel cannot be injected as intended with a not so high penetration force. Combustion worsens.
[0005]
Accordingly, an object of the present invention is to provide a fuel injection device for an internal combustion engine that can inject fuel in a hollow conical shape when the engine is under low load, and sufficiently inject the fuel with a sufficiently high penetration force when the engine is under a high load. It is to be.
[0006]
[Means for Solving the Problems]
The fuel injection device for an internal combustion engine according to claim 1 of the present invention includes a first injection hole for injecting fuel without swirling, and a second injection hole for swirling and injecting fuel. At low engine load, fuel injection is performed using only the second injection hole, and at high engine load, only the first injection hole or both the first injection hole and the second injection hole are used. The fuel injection is performed.
[0007]
Further, in the fuel injection device for an internal combustion engine according to claim 2 according to the present invention, in the fuel injection device for an internal combustion engine according to claim 1, at the time of low engine load, pilot fuel injection is performed prior to the fuel injection, The pilot fuel injection is also performed using only the second injection hole.
[0008]
According to a third aspect of the present invention, in the fuel injection control apparatus for an internal combustion engine according to the first aspect, at the time of high engine load, pilot fuel injection is performed prior to the fuel injection. The pilot fuel injection is also performed using only the first injection hole or both the first injection hole and the second injection hole.
[0009]
A fuel injection device for an internal combustion engine according to a fourth aspect of the present invention is the fuel injection device for an internal combustion engine according to the first aspect, wherein the fuel injection device is provided between the high engine load state and the low engine load state. At the time of medium load, fuel injection is performed using only the first injection hole or both the first injection hole and the second injection hole during the engine middle load.
[0010]
Further, in the fuel injection device for an internal combustion engine according to claim 5 according to the present invention, in the fuel injection device for an internal combustion engine according to claim 4, at the time of the engine middle load, pilot fuel injection is performed prior to the fuel injection, The pilot fuel injection is performed using only the second injection hole.
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a schematic sectional view showing the vicinity of the injection hole of the fuel injection device according to the present invention. Reference numeral 1 denotes a fuel injection device main body. The space in the vicinity of the injection hole in the fuel injection device main body 1 is radially divided into an inner space and an outer space by a separation wall 2. The first valve body 3 is inserted into the inner space, and the hollow second valve body 4 is inserted into the outer space so as to slide with respect to the separation wall 2.
[0012]
In the inner space, a plurality of first injection holes 5 are formed radially with respect to the central axis of the fuel injection device main body 1 inside the first seat portion 1a with respect to the first valve body 3 of the fuel injection device main body 1. I have. In the outer space, a plurality of second injection holes 6 are formed radially with respect to the center axis of the fuel injection device main body 1 inside the second seat portion 1b with respect to the second valve body 4 of the fuel injection device main body 1. ing.
[0013]
High-pressure fuel is supplied to the inner space and the outer space, and when the first valve body 3 is opened and the first seat portion 1a is opened, fuel is injected through the first injection hole 5, and When the second valve body 4 is opened and the second seat portion 1b is opened, fuel is injected through the second injection hole 6. Thus, according to the present fuel injection device, it is possible to inject fuel from both the first injection hole 5 and the second injection hole 6.
[0014]
FIG. 2 is an enlarged sectional view of the vicinity of the second injection hole 6, and FIG. 3 is a front view of the second injection hole 6 as viewed from the inside of the fuel injection device. As shown in FIGS. 2 and 3, a fuel guide groove 7 is formed eccentrically with respect to each second injection hole 6 on the inner wall of the fuel injection device main body 1 in which the second injection hole 6 is formed. This fuel guide groove is cut by, for example, moving incisors having a V-shaped or U-shaped cross section in parallel with the axis of the fuel injector main body.
[0015]
As shown in FIG. 2, the second valve body 4 lifts only slightly when the valve is opened, and only a small gap is formed with respect to the inner wall of the fuel injection device main body 1. Accordingly, when the second valve body 4 is opened, the high-pressure fuel in the outer space is unlikely to directly flow into the second injection hole 6 from this small gap, and first flows into the fuel guide groove 7. After that, it flows into the second injection hole 6. In this manner, the fuel is swirled and injected inside the second injection hole 6 as shown by a dotted line in FIGS. It becomes. By injecting the fuel in a hollow conical shape, the injected fuel is easily atomized.
[0016]
On the other hand, the first injection hole 5 is not processed like the fuel guide groove, and the lift amount when the first valve body 3 is opened is made relatively large. Thereby, when the first valve body 3 is opened, the high-pressure fuel in the inner space directly flows into the first injection hole 5 and is injected in a columnar shape. Since the first orifice 5 does not need to allow the fuel to swirl like the second orifice 6, it is not necessary to increase the diameter of the orifice so as not to hinder the swirl of the fuel. It is possible to sufficiently increase the penetration force of the fuel that is made smaller and injected as a column.
[0017]
FIG. 4 shows nine engine operating regions determined by the engine speed N and the engine load L. In the nine operating ranges, A is a low rotation low load region, B is a medium rotation low load region, C is a high rotation low load region, D is a low rotation medium load region, and E is a medium rotation low load region. F is a high rotation medium load region, G is a low rotation high load region, H is a medium rotation high load region, and I is a high rotation high load region.
[0018]
This fuel injection device is used, for example, in a diesel engine, and radially injects fuel from a plurality of injection holes into a cavity formed on a piston top surface from substantially the center of an upper portion of a cylinder. In the regions A and B in the nine operating regions described above, only the second valve body 4 is lifted, and the fuel is injected in a hollow conical shape through the second injection holes 6. At this time, if the fuel injection amount is relatively small and the fuel is widely dispersed in the cavity, ignition and combustion will not be performed well. Thereby, the fuel can be satisfactorily ignited and burned by lowering the penetration force so as not to disperse the fuel much and promoting atomization of the fuel by spraying in a hollow cone shape.
[0019]
Further, in the other regions C, D, E, F, G, H, and I, since the fuel injection amount is relatively large, dispersing the fuel over a wide area in the cavity increases the air utilization rate. Combustion can be improved. As a result, only the first valve body 3 is lifted, and fuel is injected in a columnar shape through each first injection hole 5. In the present fuel injection device, as described above, the diameter of the first injection hole 5 is set so as to sufficiently increase the penetration force since it is not necessary to pass the swirling fuel. Thus, according to the first injection hole 5, a columnar fuel injection with a high penetration force is possible, and even if the intake air amount is large and the pressure in the cylinder at the end of the compression stroke, which is the fuel injection timing, is very high, the injected fuel can be injected. In addition to being able to be dispersed over a wide area of the cavity, the injected fuel generates a large frictional force with the intake air due to the high penetration force, and is sufficiently atomized by the frictional force, thereby achieving good combustion. be able to.
[0020]
By the way, since the injected fuel ignites and burns at once, a large noise is generated. Therefore, it is known that a necessary amount of fuel is divided and injected first as pilot fuel injection. In a case where such pilot fuel injection is performed in each of the above-described operation regions, in regions A and B, the pilot fuel injection is also performed using the second injection holes 6 in the same manner as in the above-described main fuel injection. Is injected in a hollow conical shape. At this time, the required amount of fuel combined with the pilot fuel injection and the main fuel injection is not so large, and in order to realize reliable ignition combustion, the pilot injection fuel and the main injection fuel must not be dispersed with each other. Instead, the pilot fuel injection is also injected in a hollow cone shape having a low penetration force in accordance with the main fuel injection.
[0021]
In the regions C, D, E, and F, the pilot fuel injection uses the second injection hole 6 to inject the fuel in a hollow conical shape, unlike the main fuel injection described above. At this time, in order to increase the required amount of fuel, it is preferable to increase the air utilization rate by dispersing the fuel over a wide area in the cavity, whereby the pilot fuel injection is performed as a hollow cone having a low penetration force. Inject and position the well atomized fuel near the fuel injection device in the cavity, and in the subsequent main fuel injection, inject the fuel as a columnar shape with high penetrating force, near the periphery in the cavity separated from the fuel injection device The fuel finely atomized by the large frictional force with the intake air is located in the cavity so that the fuel is widely dispersed in the cavity.
[0022]
In the regions G, H, and I, the pilot fuel injection also uses the first injection holes 5 to inject fuel in a columnar manner, similarly to the main fuel injection described above. At this time, since a large amount of intake air is supplied into the cylinder, the in-cylinder pressure at the time of fuel injection is extremely high, and the fuel is injected as a hollow cone having a low penetration force in the pilot fuel injection. Will be concentrated in the immediate vicinity of. Also, at this time, the required amount of fuel including the pilot injection fuel and the main injection fuel is large, and the pilot injection fuel amount is relatively large. As a result, in this fuel injection device, the pilot injection fuel is also injected in a columnar shape having a high penetrating force, and the fuel atomized by the large frictional force with the intake air during flight collides with the peripheral wall of the cavity and rebounds to repel the cavity. It is located in the center, and then the main injected fuel is similarly injected in a columnar shape with high penetrating force, and before and after the fuel atomized by the frictional force with the intake air collides with the peripheral wall of the cavity, It can be located near a wall. Thus, a large amount of fuel can be widely dispersed in the cavity, and good combustion with high air utilization can be realized.
[0023]
In the high rotation and high load region I, a large amount of required fuel must be injected in a short time associated with high rotation, and it is difficult to provide a time interval between the pilot fuel injection and the main fuel injection. , The pilot fuel injection may not be performed.
[0024]
In the present fuel injection device, when the fuel is injected by the first injection hole 5 in a columnar shape having a high penetration force, the fuel may be simultaneously injected by the second injection hole 6. In the pilot fuel injection or the main fuel injection, when the fuel is injected in a columnar shape, the amount of injected fuel is relatively large, and the fuel is injected by the second injection hole 6 in addition to the first injection hole 5, so that the fuel is injected in a short time. The required amount of fuel in the pilot fuel injection or the main fuel injection can be injected, so that, for example, the pilot fuel injection can be reliably performed even in the high rotation and high load region I. The fuel injection through the second injection hole 6 increases the lift amount of the second valve body 4 and increases the fuel introduction groove 7 even if the lift amount of the second valve body 4 is reduced and the fuel is injected in a hollow conical shape. Alternatively, the fuel may be directly injected into the second injection hole 6 without passing through the fuel, and the fuel may be injected in a columnar shape.
[0025]
As described above, in the present fuel injection device, the column-shaped fuel injection using the first injection hole 5 and the hollow conical fuel injection using the second injection hole 6 can be respectively performed. The present invention is not limited thereto, and it is sufficient that at least only the fuel injection in the shape of a hollow cone using the second injection hole 6 can be independently performed. For example, only one valve body is provided, and by lifting this valve body small, the columnar fuel injection hole corresponding to the first injection hole 5 of the present fuel injection device is still closed. The conical fuel injection hole corresponding to the second injection hole 6 of the fuel injection device is opened, fuel is injected in a hollow conical shape, and the valve body is further lifted, whereby the columnar fuel injection hole is formed together with the conical fuel injection hole. It is also possible to apply the present invention to a fuel injection device in which the injection hole is also opened and fuel is injected in a columnar shape having a high penetration force by the columnar fuel injection hole in addition to the conical fuel injection hole. In this fuel injection device, when the conical fuel injection hole has the same fuel guide groove 7 as the second injection hole 6, the valve body is largely lifted to supply the fuel by the columnar fuel injection hole. When the fuel is injected, the fuel is also injected in a column shape by the conical fuel injection nozzle.
[0026]
In the case where such a fuel injection device is used, in the above-described embodiment, when the fuel is injected into the column by the first injection hole 5, the valve body is largely lifted, and the fuel injection by the conical fuel injection injection hole is performed. In addition to this, the fuel is injected in a columnar shape having a high penetration force by the columnar fuel injection nozzles. In such a fuel injection, when the valve body is lifted small while the valve body is lifted largely, fuel is injected in a hollow conical shape from the conical fuel injection injection hole, and thereafter, the valve body is lifted greatly. The fuel is injected in a column shape from the columnar fuel injection holes.
[0027]
As described above, the reason why the fuel is injected in a columnar shape having a high penetration force is to distribute the fuel over the entire cavity in the pilot fuel injection and the main fuel injection. Thus, if the fuel is injected in a hollow cone shape having a low penetration force at the beginning of the fuel injection, this fuel is located near the fuel injection device, and the injected fuel thereafter is injected into the peripheral portion of the cavity by the high penetration force. Position, which is advantageous for distributing the fuel throughout the cavity.
[0028]
【The invention's effect】
As described above, the fuel injection device for an internal combustion engine according to the present invention includes the first injection hole for injecting fuel without swirling, and the second injection hole for swirling and injecting fuel. At low engine load, fuel injection is performed using only the second injection hole, and at high engine load, fuel injection is performed using only the first injection hole or both the first and second injection holes. It is supposed to. Thereby, at the time of low engine load, fuel can be injected in a hollow conical shape using only the second injection hole, and at the time of high engine load, at least the first injection hole provided separately from the second injection hole is used. The fuel can be injected in a columnar shape with sufficiently high penetration force by the first injection hole.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view in the vicinity of an injection hole of a fuel injection device according to the present invention.
FIG. 2 is an enlarged sectional view in the vicinity of a second injection hole in FIG.
FIG. 3 is a front view of the second injection hole as viewed from the inside of the fuel injection device.
FIG. 4 is a map showing nine operating regions determined by an engine speed and an engine load.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Fuel injection device main body 3 ... First valve body 4 ... Second valve body 5 ... First injection hole 6 ... Second injection hole 7 ... Fuel guide groove

Claims (5)

A first injection hole for injecting fuel without swirling and a second injection hole for swirling and injecting fuel are provided. When the engine is under low load, fuel injection is performed using only the second injection hole. And performing fuel injection using only the first injection hole or both the first injection hole and the second injection hole at a high engine load. The fuel for an internal combustion engine according to claim 1, wherein pilot fuel injection is performed prior to the fuel injection when the engine is under a low load, and the pilot fuel injection is also performed using only the second injection hole. Injection device. At the time of high engine load, pilot fuel injection is performed prior to the fuel injection, and the pilot fuel injection is also performed using only the first injection hole or both the first injection hole and the second injection hole. The fuel injection control device for an internal combustion engine according to claim 1, wherein: During the high engine load and the low engine load, there is an intermediate engine load, and at the engine medium load, only the first injection hole or both the first injection hole and the second injection hole The fuel injection device for an internal combustion engine according to claim 1, wherein the fuel injection is performed by using a fuel injection device. The fuel for an internal combustion engine according to claim 4, wherein a pilot fuel injection is performed prior to the fuel injection at the time of the engine medium load, and the pilot fuel injection is performed using only the second injection hole. Injection device.

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