JPH11159424A - Fuel injection device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce port wet of fuel spray while suppressing that atomized fuel is enlarged again. SOLUTION: A injector 18 for injecting and supplying fuel to the intake port 17 of an engine 1 is so arranged that the nozzle hole part thereof is positioned in the center part of the intake port 17. The injector 18 inject fuel by taking aim at the umbrella 14a of an intake valve 14. The nozzle hole part of the injector 18 is made porous, thereby fuel spray is atomized. The spraying angle of the injector 18 is regulated in the range of from 8 to 15 deg.. In this case, most fuel is led to flow into the inside of an air cylinder through the center part of the intake port 17 where a flow speed is high, therefore port wet can be reduced. The nozzle hole part of the injector 18 is directed to the center part of the intake port 17 and fuel is injected by taking aim at the umbrella part 14a of the intake valve 14 therefore, a fuel spraying angle of fuel can be enlarged under a condition having no port wet. As a result, it can suppress that particles are enlarged again by the interference of a streamline of fuel spray.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device for an internal combustion engine, in which a fuel injection port is made fine by making an injector nozzle orifice porous and atomized fuel is injected into an intake port.

[0002]

2. Description of the Related Art Conventionally, various techniques for atomizing fuel injected by an injector have been embodied for the purpose of reducing unburned HC in exhaust gas and stabilizing combustion. For example, an injector in which a fuel injection port is made porous, and an injector in which atomization is promoted by using a differential pressure on the upstream and downstream sides of a throttle valve are embodied.
Note that, at present, porous injectors are being used more and more because the number of parts and costs are reduced. It has been found that existing porous injectors can achieve the effect of atomizing the fuel even if the fuel pressure is relatively low (for example, about 300 to 500 kPa).

[0003]

However, in the injector in which the injector orifice is made porous, atomization of the spray can be achieved by narrowing the stream line per one ejected from each hole of the orifice. However, if each of these atomized streamlines interferes with each other, the particles will re-enlarge. In such a case, when the particle size increases, the atomization effect of the fuel spray decreases, so that it is necessary to increase the spray angle of the injector to avoid re-enlargement of the fuel particles.
However, when the spray angle is increased, the fuel spray collides with the port wall portion and tends to adhere thereto, which causes a problem that the port wet amount increases.

The present invention has been made in view of the above problems, and an object of the present invention is to reduce port wetness of fuel spray while suppressing re-enlargement of atomized fuel. An object of the present invention is to provide a fuel injection device for an internal combustion engine.

[0005]

In order to achieve the above object, according to the first aspect of the present invention, a fuel for an internal combustion engine is provided in which an injector orifice is made porous and fuel is injected from an injector to an intake port. In the injector, the injector orifice is located at the center of the intake port, and the injector is arranged so that fuel is injected at the umbrella of the intake valve. Further, the injector is arranged in accordance with the diameter of the umbrella of the intake valve. The fuel spray angle is set according to the following.

[0006] In short, there are regions with different air velocities in the intake port through which the intake air flows, and the flow velocity is generally higher at the port center. Therefore, in order to get on the high-speed air flow, the injector orifice portion is set forward, and fuel is injected at the center of the port. In this case, most of the fuel flows into the cylinder while riding on the mainstream portion having a high flow velocity, so that port wet is reduced. On the other hand, since the injector orifice is advanced to the center of the intake port and the fuel is injected toward the umbrella of the intake valve, when the fuel spray is atomized by making the injector orifice porous, the port wet The spray angle of the fuel can be expanded in a state where no fuel is sprayed. As a result, re-enlargement of particles due to interference of streamlines of fuel spray can be suppressed. The spray angle of the fuel by the injector may be set according to the diameter of the head of the intake valve. By setting the spray angle, it is possible to achieve the object of the present invention such as to reduce the port wet of the fuel spray while suppressing the re-enlargement of the atomized fuel.

According to a second aspect of the present invention, in a fuel injection device for an internal combustion engine in which an injector injection port is made porous and fuel is injected from an injector to an intake port, the injector injection port is formed of an intake port. The injector is located so as to be located at the center, and the fuel is injected at the head of the intake valve, and the spray angle of the fuel by the injector is restricted within a range of 8 to 15 °.

By setting the spray angle (spray angle = 8 to 1)
5 [deg.]), As in the first aspect of the present invention, it is possible to achieve the object of the present invention of reducing the port wetness of fuel spray while suppressing the re-enlargement of atomized fuel. Here, the spray angle = 8 ° corresponds to the lower limit value of the spray angle for suppressing the re-enlargement of the atomized fuel. However, when the suppression of the re-enlargement is emphasized, the spray angle is within the above range. Spray angle is 12 ~
The angle may be limited to about 15 °. Spray angle = 15 °
Corresponds to the upper limit of the spray angle for avoiding the port wet. However, when the avoidance of the port wet is emphasized, the spray angle may be limited to, for example, about 8 to 10 ° in the above range.

However, the range of the spray angle of 8 to 15 ° is as follows.
It is a general numerical value derived by experiments by the present inventors, for example, if the diameter of the valve head is increased, or if the distance between the injector nozzle and the head of the intake valve is shortened, that much. The angle range may be shifted to the extension side.

According to a third aspect of the present invention, in a fuel injection device employing a multi-directional jet type injector for simultaneously injecting fuel into a plurality of intake valves, an intake passage corresponding to the plurality of intake valves is defined. The cylinder head partition wall for performing the operation is retracted with respect to the injector nozzle port. By retracting the partition wall of the cylinder head, it is possible to eliminate a factor that hinders the injector outlet from being advanced to the center of the port.

According to a fourth aspect of the present invention, in the fuel injection device for an internal combustion engine in which the injector orifice is made porous and fuel is injected from the injector to the intake port, the injector is aimed at the head of the intake valve. It is mounted on the cylinder head of the engine, and the injector nozzle is located close to the head of the intake valve. In this case, the fuel spray angle can be set at a relatively large angle by bringing the injector injection port closer to the intake valve. This is a very effective means for suppressing the re-enlargement of the atomized fuel and reducing the port wetness of the fuel spray. As a result, the object of the present invention is achieved as described above.

According to the fourth aspect of the present invention, the optimum value of the spray angle of the injector is set to 20 to 20 as described in the fifth aspect.
It is desirable to set the angle within a range of 30 °, and the above-mentioned effect can be surely obtained at this spray angle. The reason why the lower limit value of the spray angle is set to a relatively large value (20 °) is as follows. In other words, in the case of the fourth aspect of the present invention, since the injector orifice portion is close to the valve head portion, the spray angle does not become so small as to cause the re-enlargement of the atomized fuel (re-enlargement is reliably performed). Can be prevented). Therefore, the spray angle is set to 20 ° in order to realize uniform fuel spray.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment of the present invention will be described below with reference to the drawings.

The device according to the present embodiment is for optimally controlling the fuel injection amount of a gasoline-injection type internal combustion engine. An injector for injecting and supplying fuel to each cylinder is provided by an electronic control mainly comprising a microcomputer. Equipment (hereinafter referred to as EC
U) controls its driving. In particular, in the present embodiment, the injection fuel of the injector is atomized by making the injector injection port portion porous. Further, the injector tip is extended so that the injector orifice is located at the center of the intake port. Hereinafter, details of the present apparatus will be described.

FIG. 1 is an overall configuration diagram showing an outline of a fuel injection control device according to the present embodiment. In FIG.
The internal combustion engine is configured as a four-cylinder four-cycle engine (hereinafter, simply referred to as engine 1), and an intake pipe 2 and an exhaust pipe 3 are connected to the engine 1. The intake pipe 2 is provided with a throttle valve 5 linked to an accelerator pedal 4, and the opening of the throttle valve 5 is detected by a throttle opening sensor 6. Further, an intake pressure sensor 8 is provided in the surge tank 7 of the intake pipe 2.

A piston 10 reciprocating in the vertical direction in the figure is disposed in a cylinder 9 constituting a cylinder of the engine 1, and the piston 10 is connected to a crankshaft (not shown) via a connecting rod 11. . A combustion chamber 13 defined by a cylinder 9 and a cylinder head 12 is formed above the piston 10. The combustion chamber 13 is connected to the intake pipe 2 and the exhaust pipe 3 via an intake valve 14 and an exhaust valve 15. Communicating.

A limiting current type air-fuel ratio which outputs a wide-range and linear air-fuel ratio signal in proportion to the oxygen concentration in the exhaust gas (or the concentration of carbon monoxide or the like in the unburned gas) is provided to the exhaust pipe 3. An A / F sensor 16 composed of a sensor is provided. The cylinder 9 (water jacket) is provided with a water temperature sensor 23 for detecting a cooling water temperature.

An intake port 17 of the engine 1 is provided with an electromagnetically driven injector 18, and fuel (gasoline) is supplied to the injector 18 from a fuel tank 19. In the present embodiment, a multipoint injection (MPI) system having one injector 18 for each branch pipe of the intake manifold is configured, and the injector 18 of each cylinder is provided with a delivery pipe 25.
Are connected by In the present embodiment, a porous injector 18 is employed, and its detailed configuration will be described later. Between the fuel tank 19 and the injector 18, a fuel pump 26 for feeding fuel to the delivery pipe 25 while adjusting fuel pressure (fuel pressure) is provided.

The ignition plug 27 disposed in the cylinder head 12 is ignited by a high voltage for ignition from an igniter 28. The igniter 28 has a distributor 2 for distributing the high ignition voltage to the ignition plug 27 of each cylinder.
0 is connected to the distributor 20, a reference position sensor 21 that outputs a pulse signal at every 720 ° CA according to the rotation state of the crankshaft, and a pulse at each finer crank angle (eg, every 30 ° CA). A rotation angle sensor 22 that outputs a signal is provided.

In this case, the fresh air supplied from the upstream of the intake pipe and the fuel injected by the injector 18 are mixed with the intake port 17.
, And the air-fuel mixture flows into the combustion chamber 13 (inside the cylinder 9) with the opening operation of the intake valve 14. Then, the air-fuel mixture flowing into the combustion chamber 13 is provided for combustion by the ignition spark of the ignition plug 27.

The ECU 30 is mainly composed of a well-known microcomputer system, and includes a CPU 31, a ROM 3
2, a RAM 33, a backup RAM 34, an A / D converter 35, an input / output interface (I / O) 36, and the like. The throttle opening sensor 6, the intake pressure sensor 8,
Each detection signal of the A / F sensor 16 and the water temperature sensor 23 is
The signal is input to the A / D converter 35, A / D converted, and taken into the CPU 31 via the bus 37. The pulse signals from the reference position sensor 21 and the rotation angle sensor 22 are taken into the CPU 31 via the input / output interface 36 and the bus 37.

The CPU 31 determines the throttle opening TH, the intake pressure PM, and the air-fuel ratio (A
/ F), a coolant temperature Tw, a reference crank position (G signal), and an engine operation state such as an engine speed Ne are detected. Further, the CPU 31 calculates a control signal such as a fuel injection amount and an ignition timing based on an engine operating state, and outputs the control signal to the injector 18 and the igniter 28.
In particular, during injector control, fuel is injected within a predetermined period during which the engine 1 shifts from the exhaust stroke to the intake stroke, and this injected fuel is injected into the cylinder (in the combustion chamber 13) with the opening of the intake valve 14 during the intake stroke. Inflow.

Next, a detailed configuration of the injector 18 will be described with reference to FIG. The injector 18 of the present embodiment is configured as an electromagnetic normally-closed valve.
In a substantially cylindrical valve body 41, an injection port 45 for injecting fuel into the intake pipe 2 is formed at a tip (lower end in the figure) of the valve body 41, and a valve body 42 can slide inside the valve body 41. Is formed with a sliding hole 46 to be accommodated therein. A valve seat 47 having a conical surface is formed between the injection port 45 of the valve body 41 and the sliding hole 46. The length of the circular tube portion 41a of the valve body 41 is longer than that of a conventional general tube.

At the tip of the valve body 41, a plate 44 constituting a perforated injection port is mounted. The plate 44 includes two intake valves 14 for each cylinder.
Are branched in two directions so as to face the center of the umbrella portion 14a, and have, for example, a total of 12 nozzles. Specifically, as shown in FIG. 3, the injector 18 is configured by a so-called two-jet injector in which fuel is injected from two ends in two directions.

The needle-shaped valve body 42 has sliding contact portions 51a and 51b formed at two axial positions thereof. The sliding contact portions 51a and 51b contact the inner peripheral surface of the sliding hole 46. Thus, the valve element 42 slides in the sliding hole 46. In the valve element 42, flat portions 52a and 52b are formed at portions adjacent to the sliding contact portions 51a and 51b in the circumferential direction, and the flat portions 52a and 52b and the inner peripheral surface of the sliding hole 46 are formed. The fuel flows through the gap formed therebetween.

The valve body 42 includes a valve seat 4 of the valve body 41.
7 is formed in contact with the valve body 42.
The valve closing position (position shown) in which the contact portion 53 contacts the valve seat 47 to close the injection port 45, and the contact portion 53 opens the injection port 45 by separating from the valve seat 47 by a predetermined amount. Between the open position and the open position.

On the other hand, a ring-shaped stopper 54 is provided on the upper end surface of the valve body 41 in the figure,
2 is inserted through the stopper 54 and protrudes toward the casing 55. Here, a flange 56 that protrudes in the circumferential direction is formed on the valve body 42, and when the valve body 42 is pulled up by driving of the electromagnetic actuator 43, the flange 56 hits the stopper 54 and the valve opening position of the valve body 42 is set. Be regulated.

The electromagnetic actuator 43 housed in the casing 55 is roughly divided into a core (armature) 57,
It is composed of a stator 58 and an electromagnetic coil 59.
The core 57 is integrally movably connected to the valve body 42, and is constantly urged by the return spring 60 toward the valve closing side (the lower side in FIG. 2) of the valve body 42. A stator 58 made of a cylindrical magnetic material is arranged coaxially with the core 57, and is fixed to the casing 55 by a flange portion 58 a being caulked by an end of the casing 55. A circular tubular body 61 is disposed in the stator 58. An inflow port 62 for inflowing fuel is formed in an upstream portion of the cylindrical body 61, and a filter 63 is provided in the inflow port 62.

The electromagnetic coil 59 has an external (ECU 30)
A terminal 64 for taking in a control signal from is connected. The terminal 64 is supported in a connector 65, and the connector 65 is formed of a mold resin 66 provided at an end of the casing 55.

In the injector 18 configured as described above, when fuel flows in from the inflow port 62, the fuel slides through the filter 63, the cylinder 61, the core 57, and the gap between the stopper 54 and the valve 42. It is guided into the hole 46.
When the electromagnetic coil 59 is energized by the ECU 30, a magnetic force is generated and the core 57 is returned to the return spring 60.
2 is lifted upward in FIG. As a result, the gap between the valve seat 47 and the contact portion 53 is opened, and the fuel is supplied through the injection port 45 and the plate 44 to the intake port 1.
7 is injected.

The gist of the fuel injection control device configured as described above is to adopt the following configurations (a) to (d). (A) The injector 18 performs “intake stroke synchronous injection”. (B) The injector injection port is made porous to atomize the fuel. (C) The tip of the injector 18 is extended, and the injector orifice is extended to the center of the intake port 17. (D) The spray angle of the injector 18 is regulated at a predetermined angle. Hereinafter, the configurations (a) to (d) will be described in detail.

First, (a) will be described. That is, according to the intake stroke synchronous injection, fuel is injected and supplied to the intake port 17 within a predetermined period during which the engine 1 shifts from the exhaust stroke to the intake stroke, and the injected fuel is used to open the intake valve 14 during the intake stroke. Flows into the combustion chamber 13. In this case, the intake air is cooled by the vaporization of the fuel when the air-fuel mixture flows into the combustion chamber 13, and the charging efficiency of the intake air is improved by this vaporization cooling effect.

The above (b) will be described. Engine 1
In order to increase the combustion efficiency of the fuel cell, draw out a larger torque, and suppress the emission to a low level, it is preferable to make the mixture produced in the combustion chamber 13 as uniform as possible. As one of the methods, the injector nozzle is made porous so that the fuel spray is atomized. Specifically, the air pressure is not used and the fuel pressure is the same as in the normal state (fuel pressure = 300 to 500).
kPa), fuel particle size (Sauter mean particle size SMD: Saut
er's mean diameter) to about 50 μm.

The above (c) will be described. in short,
There are regions in the intake port 17 where the air flow rates are different,
Usually, it is considered that the air flow velocity is higher in the port center than in the vicinity of the wall. The distribution of the flow velocity in the intake port 17 has been confirmed by the inventors through a simulation experiment such as a Schlieren visualization test for observing the air flow.

Therefore, in the present embodiment, the injector 1
The valve body 41 of FIG. 8 is extended (see FIG. 2), and the injector 18 is disposed so as to protrude so that the tip (injection port) of the injector 18 is located at the center of the intake port 17. Here, the injector 18 is disposed toward the umbrella portion 14a of the intake valve 14. In such a case, the fuel spray of the injector 18 flows on the main flow portion (region where the flow velocity is high) of the intake air flowing in the intake port 17. This fuel spray flows without stagnation in the intake port 17 and flows into the combustion chamber 13 together with the intake air with the opening of the intake valve 14.

FIG. 5 shows an example of a simulation study of the fuel spray at the intake port 17. “A⇔B” in the figure
Each of the areas straddling indicates that the fuel concentration is different. The fuel concentration is higher on the A side (port center portion), and the fuel concentration is lower on the B side (outside the port). That is, since the injector 18 is advanced to the center of the port, much of the fuel is supplied to the center of the port having a high air flow rate, and flows into the cylinder as the intake valve 14 opens. It can be seen that almost no fuel is present near the port wall surface where the intake flow velocity is slow.

The above (d) will be described. As described above, when the injector 18
The spray angle γ of the injector 18 shown in FIG. 4 is set in the range of γ angle = 8 to 15 °. γ angle =
8 ° corresponds to the lower limit of the spray angle for suppressing the re-enlargement of the atomized fuel, and γ angle = 15 ° corresponds to the upper limit of the spray angle for avoiding the port wet.

On the other hand, in FIG. 3, the spray angles α and β that determine the spray characteristics of the two-jet injector are set within the ranges of α angle = 18 to 22 ° and β angle = 46 to 51 °, respectively. The angles α and β are restricted by the partition wall 12a of the cylinder head 12 that separates the two intake valves 14, and at this time, the partition wall 12a is retracted as much as possible. As a result, it is possible to eliminate a factor that hinders the injection of the injector nozzle to the port center.

Specific conditions in the actual machine, such as the above-described values of the spray angles α, β, and γ, and the mounting position of the injector 18 (the above-mentioned position) are obtained mainly based on simulation calculations and visualization studies. . For example, injector 18
Is preferably set according to the diameter of the head portion 14a of the intake valve 14. Incidentally, in the present embodiment, the diameter of the valve head 14a is 29 mm, and the spray angle is set so that fuel injection is performed toward the head 14a.

In the fuel injection control device having the above-described structure, when the fuel is injected by the injector 18, the fuel is injected and supplied to the intake port 17 at the umbrella portion of the intake valve 14, and the fuel is injected into the main flow portion of the intake port 17 (region where the flow velocity is large). Ride the fuel spray. At this time, most of the fuel passes through the valve gap at the time of opening the valve and flows into the combustion chamber 13 as it is, and the remaining fuel collides with an airflow into the valve head portion 14a and the like to be pulverized and atomized. 13 flows into. Since there is no fuel near the port wall surface where the flow velocity is relatively slow, the port wet is reduced as compared with the existing device. By reducing the port wet, a torque increase is achieved.

In such a case, the spray angle γ of the fuel can be expanded without the port wet. as a result,
The re-enlargement of particles due to interference of stream lines of fuel spray can be suppressed, and the object of the present invention can be achieved.

FIG. 6 is an experimental result showing the relationship between the spray angle γ and the fuel inflow rate (%) into the cylinder for SMD = 20 μm and 50 μm, respectively. SMD in the figure = 50
The three μm data show the results of each experiment depending on the difference in the front position of the injector. According to the figure, it is understood that a high fuel inflow rate can be obtained by setting the spray angle γ to 8 to 15 ° in the case of the fuel spray having the fuel particle diameter SMD = 50 μm level. However, when SMD = 20 μm, a high fuel inflow rate can be maintained even if the spray angle γ is changed in a range of, for example, 10 to 40 °.

FIG. 7 shows a comparison between a device in which the injector 18 is advanced and a device in which the injector 18 is not advanced (non-advanced conventional device) due to the fuel vaporization cooling effect in the intake stroke synchronous injection. It is an experimental result. According to the figure, it can be seen that the above-mentioned one has a larger torque-up amount. This means that the fuel injected by the injector 18 has flowed well into the cylinder.

On the other hand, when the port wet is reduced as described above, the air-fuel ratio spike at the time of engine transition is greatly improved. The result of confirming this effect with a real machine will be described with reference to FIG. The experimental results shown in FIG.
m, Tw = 20 ° C., air-fuel ratio = stoichiometric, the intake pipe pressure is increased / decreased under the condition without low-temperature correction to generate a lean spike or a rich spike in the air-fuel ratio. In this experiment, during the lean spike of the air-fuel ratio, as shown in FIG.
mmHg to 600mmHg step by step,
Conversely, during the rich spike of the air-fuel ratio, as shown in FIG. 9B, the intake pipe pressure is increased from 600 mmHg to 400 mHg.
mHg is changed stepwise.

The vertical axis of FIG. 8 shows the air-fuel ratio of the device in which the injector orifice is set in advance (△) and the device (そ う) in which the injector is not extended at the time of lean or rich spike. The deviation width ΔA / F (lean peak, rich peak) is plotted. The horizontal axis in FIG. 8 represents the crank angle of the engine 1. In FIG. 8, each of the injection end timings in consideration of the time until the fuel flows into the cylinder is indicated by the intake T
ΔA / F at these crank angles is shown as 30 ° CA before DC, 120 ° CA after intake TDC (center of intake valve opening), and 30 ° CA after compression TDC.

According to FIG. 8, in both cases of the lean and rich spikes, the air-fuel ratio deviation ΔA / F (peak value) is smaller in the above-mentioned apparatus than in the apparatus not so, and the wet amount is small. It can be seen that the effect of the reduction is obtained. It should be noted that the optimization of the spray angle also makes the air-fuel ratio lean,
It has been confirmed that the rich peak becomes smaller.

When the injection end timing is set before the intake valve is opened (the leftmost plot point in FIG. 8) so that fuel flows into the cylinder at the beginning of the intake stroke, the air-fuel ratio deviation ΔA /
F was found to be the smallest. It is considered that this is because the fuel is hardly attached to the port wall surface by riding the relatively fast airflow immediately after the opening of the valve by terminating the injection immediately before the opening of the intake valve. From this result, deterioration of the emission due to the air-fuel ratio deviation during the transition is suppressed.
It has been confirmed that this phenomenon can be obtained even when the cooling water temperature Tw is as high as 80 ° C.

Incidentally, in the apparatus according to the present embodiment, a new injector 18 is embodied by extending the tip of the injector, but its characteristics and performance are the same as those of the conventional type. Also, the characteristics of the engine should be the same, and care should be taken not to affect the current performance.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. However,
In the configuration of the second embodiment, the same components as those in the above-described first embodiment are denoted by the same reference numerals in the drawings, and the description is simplified.

In this embodiment, FIGS. 10A and 10B
The injector 18 is directly mounted on the cylinder head 12 while aiming at the head of the intake valve 14 as shown in FIG. Further, by mounting the injector 18 on the cylinder head 12, the injector orifice is brought closer to the intake valve 14. Here, the partition wall 12a of the cylinder head 12 is retracted so that the fuel spray does not interfere with the wall surface.

The injector 18 injects fuel from a position approximately 40 to 50 mm away from the umbrella portion 14a of the intake valve 14 so that the fuel is put in the airflow aiming at the umbrella portion. Most of the fuel flows into the combustion chamber 13 from the gap of the intake valve 14 by the airflow, and the remaining fuel collides with the high-temperature valve surface, is atomized, and then flows into the combustion chamber 13.

In this case, the fuel spray angle γ can be set at a relatively large angle by bringing the injector nozzle close to the valve head 14a. This is a very effective means for suppressing the re-enlargement of the atomized fuel and reducing the port wetness of the fuel spray. The optimum value of the spray angle γ is 20-3
The angle is set in the range of 0 °, and at this γ angle, the above-mentioned effects such as prevention of re-enlargement of the fuel and reduction of the wet amount can be reliably obtained. The γ angle = 20 ° is a lower limit value for realizing uniform fuel spray, and the γ angle = 30 ° is an upper limit value for avoiding port wet.

The embodiment of the present invention can be realized in the following modes other than the above. In each of the above embodiments, the two-jet type injector that simultaneously injects fuel into the two intake valves 14 is embodied. Alternatively, for example, a one-jet type or three-jet type injector may be embodied. Good.

In the above embodiment, the intake stroke synchronous injection was performed, but this will be changed. Even in the case of “out-of-intake-stroke injection” in which fuel is injected when the intake valve 14 is closed, the fuel that collides with the valve head is divided into fine particles by injecting fuel at the spray angle aimed at by the head of the intake valve 14. Be transformed into Therefore, fuel wall adhesion (port wet) is greatly reduced.

In the first embodiment, the spray angle γ of the injector 18 is restricted in the range of 8 to 15 °, but this is changed. For example, when emphasis is placed on suppressing the re-enlargement of atomized fuel, the spray angle γ is set to, for example,
Limit to about 5 °. When importance is placed on avoiding port wet, the spray angle γ is set to, for example, 8 to 10 in the above range.
Limit to about °. However, the range of γ angle = 8 to 15 ° is
It is a general-purpose numerical value derived by experiments by the present inventors, for example, if the distance between the injector orifice and the umbrella portion of the intake valve is shortened, the angular range is shifted to the extended side by that much. Is also good.

In the second embodiment, the spray angle γ of the injector 18 is restricted in the range of 20 to 30 °, but this is changed. For example, the lower limit of the spray angle γ is reduced. As described above, since the re-enlargement of the atomized fuel can be prevented even when the γ angle is about 8 °, the lower limit of the γ angle is changed to 8 °.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing an outline of a fuel injection control device for an internal combustion engine according to an embodiment of the invention.

FIG. 2 is a sectional view showing a detailed configuration of the injector.

FIG. 3 is a cross-sectional view of an intake port showing an attached state of an injector and a state of fuel spray.

FIG. 4 is a cross-sectional view of an intake port showing an attached state of an injector and a state of fuel spray.

FIG. 5 is a view showing a simulation result of fuel spray.

FIG. 6 is a graph showing a relationship between a spray angle γ and a fuel inflow rate into a cylinder.

FIG. 7 is a diagram illustrating a relationship between presence / absence of advance of an injector and output torque.

FIG. 8 shows the presence / absence of advance of the injector and the air-fuel ratio deviation amount Δ.
The figure which shows the relationship with A / F.

FIG. 9 is a diagram showing a lean spike and a rich spike in the air-fuel ratio during transient operation.

FIG. 10 is a cross-sectional view illustrating an attached state of an injector and a state of fuel spray according to a second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine (internal combustion engine), 12 ... Cylinder head, 1
2a ... partition wall, 14 ... intake valve, 14a ... umbrella part, 17 ...
Intake port, 18 ... Injector, 44 ... Plate forming the injection port of the injector.

Claims (5)

[Claims] 1. A fuel injection device for an internal combustion engine, wherein an injector orifice is made porous and fuel is injected from an injector to an intake port, wherein the injector orifice is located at a center of the intake port and an intake valve is provided. A fuel injection device for an internal combustion engine, comprising: arranging the injector so that fuel is injected at the head of the intake valve; and setting a spray angle of the fuel by the injector according to the diameter of the head of the intake valve. 2. A fuel injection device for an internal combustion engine for making an injector injection port porous and injecting fuel from an injector to an intake port, wherein the injector injection port is located at a center of the intake port and an intake valve is provided. A fuel injection device for an internal combustion engine, wherein the injector is arranged so that fuel is injected with the aim of an umbrella portion, and a spray angle of the fuel by the injector is restricted within a range of 8 to 15 °. 3. A fuel injection device to which a multi-directional jet type injector for simultaneously injecting fuel into a plurality of intake valves is applied, wherein a cylinder head partition for defining an intake passage corresponding to the plurality of intake valves is provided. 3. The fuel injection device for an internal combustion engine according to claim 1, wherein the fuel injection device is configured to retreat with respect to the injector injection port. 4. A fuel injection device for an internal combustion engine, wherein an injector injection port is made porous and fuel is injected from an injector to an intake port, wherein the injector is attached to a cylinder head of the engine so as to aim at a head portion of an intake valve. A fuel injection device for an internal combustion engine, characterized in that an injector orifice portion is close to an umbrella portion of an intake valve. 5. The fuel injection device for an internal combustion engine according to claim 4, wherein the spray angle of the injector is restricted within a range of 20 to 30 °.