JPH1061531A - Mixture forming device and engine system for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mixture forming device for an internal combustion engine, by which fuel distributing performance to respective cylinders is improved, and good operating performance is secured. SOLUTION: A mixture forming device for an internal combustion engine is provided with an intake pipe 2 provided with a plurality of branch intake pipes 2b, 2d, 2c on the downstream part and connected to an internal combustion engine 1, a throttle valve 4 arranged in the upstream part of the intake pipe 2 and for controlling the flow rate of air flowing in the intake pipe 2, and a fuel injection valve 3 arranged among respective branch intake pipes 2b, 2d, 2c and the throttle valve 4, provided with injection ports arranged in line, and for injecting fuel from the injection ports toward respective branch intake pipes in many directions. The fuel injection valve 3 is so arranged that respective injection directional axes of fuel to be injected from the injection ports may approximately coincide with main stream lines of the flows of air flowing in respective branch intake pipes 2b, 2d, 2c toward the internal combustion engine 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air-fuel mixture forming apparatus for an internal combustion engine, and more particularly to a fuel injection valve for injecting fuel from one fuel injection valve in a plurality of directions toward a plurality of cylinders of the internal combustion engine. The present invention relates to an air-fuel mixture forming device for an internal combustion engine, which is provided downstream of a throttle valve.

[0002]

2. Description of the Related Art Conventionally, in order to realize an inexpensive fuel injection device for an internal combustion engine, a fuel injection valve capable of branching and injecting fuel in multiple directions is arranged in an intake pipe assembly corresponding to each cylinder downstream of a throttle. A system for supplying fuel to a plurality of cylinders with one cylinder has been proposed. For example, JP-A-63-223364
No. 6,086,045.

On the other hand, in the conventional system using a vaporizer, the fuel is very finely divided to a particle size of about 30 μm. Further, in a so-called single-point type fuel injection system in which a fuel injection valve is arranged upstream of a conventional throttle, although the degree of atomization of fuel is inferior to the system using the carburetor, each fuel injection point is different from the fuel injection point. The distance to the cylinder can be relatively long. For this reason, in both types, the air and fuel are both easily mixed uniformly, and the air flow in the middle of the intake passage is biased as long as the amount of air distributed to each cylinder is even. Even if it does, it does not cause the air-fuel ratio variation of each cylinder.

In the above-mentioned Japanese Patent Application Laid-Open No. 63-223364, the effect of fuel adhering to the inner wall of the intake pipe on the distribution of fuel to each cylinder is pointed out.
As described in the publication, this is largely affected by the shape of the intake pipe at the branching portion toward each cylinder, and is mainly caused by the unevenness of the inner wall of the intake pipe. Therefore, it is a problem unrelated to the above-described bias of the air flow in the intake passage.

[0005] In the above-mentioned system in which the fuel injection valves for branch injection in multiple directions are arranged downstream of the throttle to supply fuel to a plurality of cylinders, the distance from the fuel branch injection point to the internal combustion engine is compared. Although the air and fuel are difficult to mix evenly due to the short length, the distribution of fuel to each cylinder is almost dominated by the branch fuel distribution performance of the multidirectional fuel injection valve itself in each direction, and is distributed to each cylinder. It is understood that the air-fuel ratio variation among the cylinders can be kept low if the amount of air flowing is uniform. JP-A-63-22336
No. 4 also points out that the amount of fuel supplied to each intake pipe is determined by the injection amount from each injection port of the fuel injection valve, and that only the variation in the diameter affects the fuel distribution between the cylinders. doing.

[0006]

However, in the above-mentioned conventional system in which the multidirectional fuel injection valve is disposed downstream of the throttle and supplies fuel to a plurality of cylinders, the variation in the air-fuel ratio among the cylinders is considered. Experimentally confirmed that the air-fuel ratio variation between the cylinders was large even though the amount of air distributed to each cylinder was equalized, although it was not always understood as described above. As a result, it has been found that the output of the internal combustion engine is reduced and the exhaust gas component is deteriorated. And when investigating the cause of the deterioration of the fuel distribution performance, the cause was found to be the disturbance of the directionality of the injected fuel due to the bias of the air flow downstream of the throttle,
It is clear that there are unresolved issues here.

On the other hand, experiments have shown that it is important that the jets of air blown into the intake passage via the auxiliary intake passage merge evenly with the fuel spray in order to suppress variations in the air-fuel ratio between the cylinders. I was assured. The configuration of the auxiliary intake passage is not disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 63-223364, and the relationship with fuel spray is not described at all. .

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a mixing system for an internal combustion engine which distributes fuel evenly to each cylinder in consideration of the relationship between the direction of fuel spray and the bias of air flow, thereby ensuring good operability. It is an object of the present invention to provide an air forming device and an engine system.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an air-fuel mixture forming apparatus for an internal combustion engine which has a plurality of branch intake pipes at a downstream portion thereof and which is connected to the internal combustion engine. A throttle valve disposed at an upstream portion of the intake pipe to control a flow rate of an airflow flowing through the intake pipe; and an injection port disposed between the branch intake pipe and the throttle valve and arranged in a line. A fuel injection valve for injecting fuel in multiple directions toward the respective branch intake pipes, wherein the fuel injection valve is substantially isosceles with an injection port formed by each injection direction axis of the fuel injection valve as an apex. A plane containing the triangular vertical bisector is arranged to also include the main streamline of the air flow flowing from the throttle valve toward the branch intake pipe.

[0010] Another feature is that the fuel injection valve comprises:
The point that each injection direction axis of the fuel injected from the injection port is disposed so as to substantially coincide with the main streamline of the air flow flowing through each of the branch intake pipes toward the internal combustion engine. . ADVANTAGE OF THE INVENTION According to this invention, since there is no deviation of air flow and it does not hinder the direction of fuel injection, the fuel distribution to each cylinder is improved, and the good operability is ensured for an internal combustion engine. An air-fuel mixture forming device and an engine system are provided.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of an air-fuel mixture forming apparatus for an internal combustion engine and an engine system according to an embodiment of the present invention. 1 illustrates a configuration of an engine system in which an air-fuel mixture forming device for an internal combustion engine according to the present embodiment is mounted on an internal combustion engine. In the figure, the air-fuel mixture forming apparatus for an internal combustion engine according to the present embodiment includes an intake pipe 2 as an intake passage, a fuel injection valve 3, a throttle valve 4, and an auxiliary intake pipe 8 as an auxiliary intake passage. You. The engine system includes an internal combustion engine 1, an air-fuel mixture forming device for the internal combustion engine, a control device 10 for controlling the fuel injection valve 3 and the like, and a fuel supply system (not shown) for supplying fuel to the fuel injection valve 3. And various sensors (described later) that detect signals for control.

More specifically, the internal combustion engine 1 is an in-line type three-cylinder engine.
Is connected to the intake pipe 2. The intake pipe 2 has three (plural) branch intake pipes 2b, 2d, and 2c radially divided around a branch point 2m at a downstream portion. The intake pipe 2 includes a fuel tank (not shown) and a pressurizing pump.
A fuel injection valve 3 for injecting fuel supplied from a fuel supply system (not shown) or the like is provided. The fuel injection valve 3 injects fuel from an injection port (injection point o). Further, a throttle valve 4 is disposed further upstream than the fuel injection valve 3 disposed in the intake pipe 2.

Further, the intake pipe 2 may have an auxiliary intake pipe 8. In this case, the auxiliary intake pipe 8 is an air passage that bypasses the throttle valve 4, and a passage valve 8 a that opens and closes the flow of intake air. And an opening 8b opening at a downstream portion of the throttle valve 4. On the other hand, in the configuration of the engine system shown in FIG. 1, an intake pipe negative pressure sensor 7 for detecting a load state of the internal combustion engine 1 is arranged in the intake pipe 2. Further, in order to detect the operating state of the internal combustion engine 1, various sensors such as a crank angle sensor (not shown) for detecting a rotation speed and a crank angle of the internal combustion engine 1, a throttle opening degree sensor 6, and a cooling water temperature sensor 9 are provided. Are located.

FIGS. 2 and 3 are a vertical sectional view and a plan view (viewed from the bottom) showing the vicinity of the nozzle of the fuel injection valve according to one embodiment of the present invention. The main body of the fuel injection valve 3 has a structure in which fuel is introduced from above and injected from the nozzle portion 30 at the tip. The fuel is controlled by a movable valve 31 which moves up and down by electromagnetic force, and 3 provided in
From the orifices serving as the individual injection ports, that is, the first cylinder orifice 32a, the second cylinder orifice 32b,
The fuel is injected from the third cylinder orifice 32c. Then, as shown in FIG. 3, three orifices (32a, 32
b, 32c) are arranged in a line (in a straight line).

FIG. 4 is a view showing a spray state of the fuel injection valve of FIG. This fuel injection valve 3 is provided at one location (ie,
Multiple orifices (i.e., injection ports) so that fuel can be injected in multiple directions (multiple directions) from the injection point o)
Are concentrated in one place, and one fuel injection valve 3
The fuel is radially injected toward each cylinder of the internal combustion engine 1 via the intake pipe 2 and the intake port 1a. That is, in FIG. 3, since three orifices are arranged in a line in a row, as shown in FIG. Injected in a fan-shaped radial plane. In other words, the fuel is supplied to the shaft nozzle 3
A substantially isosceles triangle (ob axis, base
It is jetted in a plane including the od axis which is a perpendicular bisector of ((bc), oc axis). Note that the substantially isosceles triangle may simply be a substantially triangle.

FIG. 5 is a diagram showing an internal configuration of a control device according to an embodiment of the present invention. As shown in the figure, the control device 10 includes an input circuit 191, an A / D converter 192, a central processing unit 193, a ROM 194, a RAM 195, and an output circuit 196. Input circuit 191
Receives an input signal 190 (for example, a signal from the cooling water temperature sensor 9, the throttle opening sensor 6, etc.), removes noise components from the signal, and outputs the signal to the A / D converter 192. It is for. The A / D conversion section 192 performs A / D conversion of the signal and outputs the signal to the central processing section 193. The central processing unit 193 calculates the A
It has a function of executing each control, diagnosis, and the like by fetching the / D conversion result and executing a predetermined program stored in the ROM 194. Note that the calculation result and the A / D conversion result are temporarily stored in the RAM 195, and the calculation result is output as a control output signal 197 through an output circuit 196 to be used for controlling the fuel injection valve 3 and the like. ing. However, the configuration of the control device 10 is not limited to this.

On the other hand, the control device 10 includes an intake pipe negative pressure sensor 7 for detecting a load state of the internal combustion engine 1, a throttle opening degree sensor 6 for detecting an operation state of the internal combustion engine 1, and a cooling water temperature sensor 9. Detects the detection signals from the crank angle sensor, generates a fuel injection valve drive signal 3s based on the detection results, and controls the fuel injection valve 3 accordingly. And an ignition coil (not shown) and a spark plug
(Not shown) are also controlled. That is, the control device 10
Execute combustion control of the engine system.

The pulse width (Ti) of the fuel injector driving signal 3s generated by the control device 10 is calculated by the following equation.

Ti = KM × PM + Tb (Equation 1) Here, PM is the intake pipe negative pressure measured by the intake pipe negative pressure sensor 7, and Tb is an invalid pulse width correction term of the flow rate characteristic (Qf) of the injector shown in FIG. It is. In addition, KM is a correction coefficient, which performs correction in the entire operation range of the engine system so that the air-fuel ratio becomes close to the target value. An example is shown in FIG.
Shown in

Returning to FIG. 1, the nozzle portion 30 of the fuel injection valve 3
(I.e., the injection point o) is where the intake pipe 2 branches into the branch intake pipes 2b, 2d, and 2c toward each cylinder, that is, the intake pipe 2
Of the fuel injection valve 3 (ob axis, od axis, o axis in FIG. 4).
A substantially isosceles triangle having an injection point o (ie, injection port) formed by the c-axis) as an apex (ob axis, base (bc), oc in FIG. 4)
The plane including the vertical bisector (od axis) of the throttle valve 4 extends from the throttle valve 4 toward the internal combustion engine 1 in the branch intake pipe 2b,
The main streamline of the airflow flowing inside 2d and 2c (2bj
Axis, 2dj axis, and 2cj axis). That is, the fuel injection valve has a plane including a vertical bisector of a substantially isosceles triangle having an injection port formed by each injection direction axis of the fuel injection valve as an apex, from the throttle valve toward the branch intake pipe. The configuration is such that the main streamline of the flowing airflow is also included.

In other words, the main flow lines (2bj axis, 2dj axis, 2cj) of the air flowing through each of the branch intake pipes (2b, 2d, 2c) radially branching about the branch point 2m.
Axis) is the axis of each injection direction of the fuel injection valve 3.
It can be said that it is configured so as to substantially overlap a plane including (ob axis, odd axis, oc axis). That is, the feature of the fuel injection valve according to the present invention is such that the main flow line of the air flow flowing from the throttle valve to the branch intake pipe is included in the fan-shaped radial plane having the injection port formed by the fuel injection valve at the top. In that the fuel injection valve is disposed.

In particular, as shown in FIG.
(2b, 2d, 2c) is desirably extended linearly and connected to the internal combustion engine 1 to include the main streamline of the air flow in a fan-shaped radial plane. In other words, the fuel injection valve 3 is , Each injection direction axis as the main streamline of fuel injected from the injection port (o
main streamlines (directions of the 2bj axis, 2dj axis, and 2cj axis) of the airflow flowing through each branch intake pipe (2b, 2d, 2c) toward the internal combustion engine 1 and directions of the b axis, the od axis, and the oc axis. However, it is the structure arranged so that it may correspond substantially. With this configuration, the main flow of the fuel spray is directly (or linearly) guided to the internal combustion engine 1 (that is, the intake port 1a) by the main flow of the air flow. Is prevented from sticking to the wall of the intake pipe, in other words, the relationship between the direction of the fuel spray and the bias of the air flow becomes appropriate, and the fuel (fuel spray) is evenly distributed to each cylinder. It is. This has been experimentally confirmed as described later.

That is, the air-fuel mixture forming device for an internal combustion engine according to the present invention having the above-described structure is provided in the intake pipe 2 and controls a flow rate of air flowing through the intake pipe 2. A fuel injection valve that injects fuel in multiple directions toward each cylinder of the internal combustion engine that is arranged at a downstream portion and arranged in a line, and an injection port formed by each injection direction axis of the fuel injection valve. The fuel injection valve is arranged so that a plane including a vertical bisector of a substantially isosceles triangle having a vertex also includes a main streamline of air flowing from the throttle valve toward the internal combustion engine. Features.

The above-mentioned features of the present invention will be described in detail below. First, a description will be given of a mechanism in which the bias of the air flow adversely affects the air-fuel ratio variation among the cylinders. Not all of the fuel injected from the fuel injection valve flies in the target direction, and the fuel with a small particle diameter floats around the fuel injection valve because of its small mass and low penetration force. Therefore, the air is very unstable due to the weak air flow near the injection port. As a result, which cylinder is drawn into the cylinder varies.
As a result, variations in the air-fuel ratio among the cylinders occur. On the other hand, fuel with a large particle diameter jumps out in the target direction because of its large mass and high penetration force.However, when it encounters a strong air flow with a large bias, its directionality is again disturbed, and each cylinder This causes an air-fuel ratio variation between the two.

FIG. 8 is a diagram showing the effect of the air flow in the fuel injection of the internal combustion engine on the direction of arrival of the fuel droplets.
FIG. 8A shows an air flow of 20 m / s at atmospheric pressure, and FIG.
Is an air flow of 10 m / s at atmospheric pressure, and FIG.
It is a figure which shows each state of 10 m / s of air flows under negative pressure of 00 mmHg. The result of having investigated by computer simulation the influence which the arrival direction of a fuel particle (droplet) has on the flow of air is shown. In the figure, the lower left end is the fuel injection position, the vertical axis is the fuel injection direction, and the horizontal axis is the air flow direction. As can be understood from the simulation results, the particle size of the fuel that affects the air flow increases as the air flow velocity increases and the air density (in this case, the ambient pressure) increases. I understand. Therefore, it can be said that it is important to minimize the deviation of the air flow in order to suppress the air-fuel ratio variation among the cylinders.

Next, the reason why the air flow is biased will be described. FIG. 9 is a diagram showing a computer simulation result of an air flow in the intake pipe. Throttle valve 4
3 shows the result of analyzing the air flow in the intake pipe 2 by a computer simulation when the opening degree is small. According to the result, it can be understood that the airflow flowing from the upstream to the downstream of the throttle valve 4 does not flow uniformly over the entire circumference of the throttle valve 4, but flows out toward both outer peripheral ends of the valve. Moreover, since the air pressure on the downstream side of the throttle valve is almost close to the vacuum, it has been found that the flow velocity of the air passing through the throttle valve 4 at that time becomes close to the speed of sound.

Therefore, it can be said that the air flow flows at high speed along both walls inside the intake pipe 2 and becomes extremely uneven. The bias in this case is inevitable as long as a rotary throttle valve is used. Therefore, in order to suppress the air-fuel ratio variation among the cylinders and not to disturb the directivity of the fuel injected from the fuel injection valve, the rotation direction of the throttle valve should be adjusted to the spray direction of the fuel. It is understood that it is a very important task to combine the air flows without bias.

Therefore, as a result of various studies by the inventors, as described above, a plane containing a vertical bisector of a substantially isosceles triangle having the injection port formed by each injection direction axis of the fuel injection valve as an apex is described. It has been found that a fuel injection valve having a row of nozzles is preferably provided so as to include the main streamline of air flowing from the throttle valve toward the internal combustion engine.

However, it is also understood that a difference may occur depending on the relationship between the rotation direction of the throttle valve and the spray direction of the fuel. Therefore, the rotation direction of the throttle valve is changed with respect to the air spray ratio of each cylinder with respect to the fuel spray direction. The variation was evaluated and evaluated experimentally. The results will be described by comparing a comparative example with an example according to the present invention. First, a comparative example will be described with reference to FIGS. FIG.
0 and FIG. 11 are a cross-sectional view and a vertical cross-sectional view showing a relationship between a throttle valve axial direction and a fuel injection direction in a comparative example. FIG.
FIG. 2 is a conceptual diagram showing the deviation of the air flow due to the direction of the throttle valve shaft and the effect on the directionality of fuel spray in the comparative example.

As shown in FIGS. 10 and 11, each injection direction axis (ob axis, od axis, oc axis) of the fuel injection valve 3 forms a vertical bisecting of an approximately isosceles triangle having an injection port as a vertex. A plane containing the line and orthogonal to the base (bc) of the substantially isosceles triangle (that is, a plane containing the od axis) is an axis 2a of the intake pipe 2 from the throttle valve 4 to the internal combustion engine 1.
The fuel injection valve 3 (that is, the injection point o) is provided so as to also include j.

In the case of such a configuration, although the fuel is uniformly injected toward the center of the intake pipe 2,
The direction with the base (bc) as the axis and the axial direction of the valve shaft 4a are:
As shown in the conceptual diagram of FIG. 12, the airflows 5a and 5b on both outer sides (wall surfaces) of the intake pipe 2 in which the throttle valve 4 opens are increased, as shown in the conceptual diagram of FIG. As a result, it was found that the fuel spray was pushed away from the outside toward the inside as indicated by arrows X and Y, and that the air-fuel ratio for each cylinder varied greatly. That is, the air-fuel ratio variation (△ A / F) of each cylinder of the comparative example is about three times as large as the allowable value depending on the operating conditions of the internal combustion engine, as shown in “Comparative Example” of FIG. It was found that the value might be shown.

On the other hand, another embodiment according to the present invention will be described with reference to FIGS. FIG. 13 and FIG.
FIG. 3 is a cross-sectional view and a vertical cross-sectional view showing a relationship between a throttle valve axial direction and a fuel injection direction in an embodiment according to the present invention. FIG.
FIG. 4 is a diagram comparing the results of an investigation on the relationship between the throttle valve axis direction and ΔA / F. As shown in FIGS. 13 and 14,
When the direction of the valve shaft 4a of the throttle valve 4 is arranged to be rotated by 90 degrees and the direction of the base (bc) and the direction of the valve shaft 4a are arranged in parallel, FIG. As shown in "Example", the air-fuel ratio variation (△ A / F) could be suppressed to within an allowable value in a wide range of operating conditions of the internal combustion engine.
In this manner, the air is evenly merged with the fuel spray to reduce the air-fuel ratio variation among the cylinders.
The experiments proved to be very important. In other words, in the prior art (Japanese Patent Laid-Open No. 63-223364), it is stated that "the only influence on the fuel distribution between the cylinders is the variation in the diameter of each injection port of the fuel injector". No configuration is disclosed.

As described above, there is an optimal relationship between the injection direction of the fuel injection valve 3 and the direction of the valve shaft 4a of the throttle valve 4, that is, the valve axis direction of the throttle valve 4 is Injection formed by fuel spray injected flat from 3
The base (bc) of a substantially isosceles triangle having the vertex at (injection point o)
With the configuration according to the present invention disposed in a relationship substantially parallel to the direction, the air-fuel ratio variation (△ A / F) could be suppressed to a small value.

That is, another feature of the air-fuel mixture forming apparatus for an internal combustion engine according to the present invention is that the valve axis direction of the throttle valve is set to be substantially parallel to the base direction of the assumed substantially isosceles triangle. Thus, the air flow in the region where the throttle opening is small is not deviated from the fan-shaped surface formed by each injection direction axis of the fuel injection valve. Therefore, as shown in FIG. 15, the use of the air-fuel mixture formation device having the configuration as in the present embodiment provides an engine system that ensures good operation in a wide range.

Incidentally, the positional relationship between the valve shaft 4a and the base (bc) is not necessarily limited to those shown in FIGS. This will be described. FIG. 16 is a conceptual diagram showing the relationship between the axial direction of the throttle valve and the fuel injection direction in another embodiment according to the present invention. FIG. 17 is a conceptual diagram showing the relationship between the axial direction of the throttle valve and the fuel injection direction according to another embodiment of the present invention. As shown in FIG. 16, the valve shaft 4a
It has been confirmed that both sides (pq) and bottom sides (bc) may be arranged substantially in parallel so as to be two opposing sides of a rectangle or a trapezoid. Further, as shown in FIG. 17, a plane (p−q) composed of the side (p−q) and the bottom side (bc) of the valve shaft 4a.
qcb) includes the injection point o, or the offset plane (p'-q'-nm) and the plane (m
-N-c-b).
A plane in which the valve shaft 4a is arranged at a position separated by an angle
It can be easily inferred that a configuration arrangement consisting of (pqnm) and a plane (mncc) may be used.

Next, a description will be given of an embodiment in which a part of the intake air is blown into the intake passage through the auxiliary intake passage (by the auxiliary air jet), bypassing the throttle valve. When the throttle valve 4 is almost fully closed, the amount of air passing through the auxiliary intake pipe 8 as the auxiliary intake passage increases as the passage opening area increases. The auxiliary intake pipe 8 is usually provided with an opening 8b as a blow-out hole opened on the wall surface of the intake pipe 2.
Air flowing through the auxiliary intake pipe 8
The opening and closing of the passage valve 8a causes a jet flow from the opening 8b to collide with the airflow flowing through the intake pipe 2. here,
When the opening area of the auxiliary intake pipe 8 is larger than the opening area of the throttle valve, the momentum of the auxiliary air jet becomes stronger, and the air flow in the intake pipe 2 is dominated by the flow of the auxiliary air. . Therefore, if the position or the direction of the opening 8b is deflected, the air flow in the intake pipe 2 will be deviated following the deflection.

Therefore, the direction of the jet of the air blown into the intake pipe 2 via the auxiliary intake pipe 8 is changed for the position of the opening 8b of the auxiliary air system passage 8, and the air-fuel ratio variation for each cylinder
Using (△ A / F) as an evaluation criterion, an experimental investigation was conducted.
This will be described. 18 and 19 are a cross-sectional view and a vertical cross-sectional view showing the relationship between the position of the passage outlet of the auxiliary air system and the fuel injection direction in the comparative example. This is the case where the position of the opening 8b on the downstream side of the auxiliary intake pipe 8 is such that the jet of air blown into the intake pipe 2 intersects the fuel spray direction.

In this comparative example, as shown in FIGS. 18 and 19, the opening 8b on the downstream side of the auxiliary intake pipe 8 is located on the first cylinder side.
(Branch intake pipe 2b side). For this reason, more air is distributed to the first cylinder side and the fuel amount is reduced, while on the other cylinder side, the displaced fuel spray is distributed more and the fuel amount is increased. It was found that ΔA / F deteriorated as described later. In other words, by appropriately setting the opening direction of the throttle valve 4 and the direction of the valve shaft 4a as described above, the ΔA / F
Can be suppressed below the allowable value. However, if the auxiliary intake pipe 8 is provided with the configuration shown in FIGS.
/ F was found to be worse.

FIGS. 20 and 21 are a longitudinal sectional view and a longitudinal sectional view showing the relationship between the position of the outlet of the auxiliary air system and the fuel injection direction in the embodiment according to the present invention. FIG. 22 is a diagram comparing the examination results of the relationship between the position of the passage outlet of the auxiliary air system and ΔA / F. As shown in FIGS. 20 and 21, the auxiliary intake pipe 8
22 is arranged so that the downstream opening 8b is located substantially at the center of the intake pipe 2. As shown in FIG. 22, according to the configuration of the present embodiment, ΔA / F is set within an allowable value. It turns out that it can be suppressed.

That is, as shown in FIGS. 20 and 21, the arrangement of the auxiliary intake pipe 8 is shifted by 90 degrees, and the opening 8b on the downstream side of the auxiliary intake pipe 8 is blown into the intake pipe 2 from the opening 8b. The jet direction of the air flow is the perpendicular bisector (od axis) described above.
Opening in the intake pipe 2 so as to substantially overlap the direction of
In other words, when the opening 8b is disposed so as to be substantially at the center of the intake pipe 2, the air-fuel ratio variation (△ A /
F) was able to be kept within the allowable value.

Therefore, another feature of the air-fuel mixture formation device for an internal combustion engine according to the present invention is that the intake pipe includes an auxiliary intake pipe for introducing air into the intake pipe by bypassing the throttle valve.
In the auxiliary intake pipe, a jet direction of air blown from the auxiliary intake pipe into the intake pipe is parallel to a fuel injection direction,
In addition, the opening is formed in the intake pipe so as to substantially overlap the direction of the perpendicular bisector of the substantially isosceles triangle.

By the way, the position of the opening 8b does not necessarily have to be as shown in FIGS. 20 and 21, and this will be described. FIG. 23 is a longitudinal sectional view showing a relationship between a passage outlet position of an auxiliary air system and a fuel injection direction according to another embodiment of the present invention. As shown in FIG. 23, the opening 8 b on the downstream side of the auxiliary intake pipe 8 connects the axis 2 aj of the intake pipe 2 from the throttle valve 4 to the internal combustion engine 1 and the injection point o (injection port) of the fuel injection valve 3. The opening 8b is located near a line (l, m, n) where the plane (2aj-o) to be included intersects the wall surface of the intake pipe 2.
It can be easily inferred that a configuration may be adopted in which the central portion of the above may be arranged.

As described above, according to the present invention, there is provided an air-fuel mixture forming apparatus for an internal combustion engine capable of uniformly distributing fuel to each cylinder in consideration of the relationship between the direction of fuel spray and the bias of air flow. In addition, in the case of an engine system using the air-fuel mixture forming device for an internal combustion engine, good operation is ensured in a wide range.

[0044]

According to the present invention, an internal combustion engine having a fuel injection valve for injecting fuel from one fuel injection valve in multiple directions toward a plurality of cylinders of the internal combustion engine in synchronization with the rotation of the internal combustion engine is provided. In the air-fuel mixture forming device for an engine, since the bias of the air flow is eliminated and the fuel injection direction is not hindered, the air-fuel mixture forming device for an internal combustion engine with good fuel distribution to each cylinder and a good air-fuel mixture forming device are provided. There is an effect that an engine system having drivability can be realized.

[Brief description of the drawings]

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

FIG. 2 is a longitudinal sectional view showing the vicinity of a nozzle of a fuel injection valve according to an embodiment of the present invention.

FIG. 3 is a plan view showing the vicinity of a nozzle of a fuel injection valve according to an embodiment of the present invention.

FIG. 4 is a view showing a spray state of a fuel injection valve of FIG. 2;

FIG. 5 is a diagram showing an internal configuration of a control device according to an embodiment of the present invention.

6 is a view showing a flow rate characteristic of the fuel injection valve of FIG. 2 controlled by the control device of FIG. 5;

FIG. 7 is a diagram showing a correction coefficient of a fuel injection pulse width of the fuel injection valve of FIG. 2;

FIG. 8 is a diagram showing an effect of an air flow in fuel injection of an internal combustion engine on a direction in which fuel droplets reach.

FIG. 9 is a diagram showing a computer simulation result of an air flow in an intake pipe.

FIG. 10 is a cross-sectional view illustrating a relationship between a throttle valve axial direction and a fuel injection direction in a comparative example.

FIG. 11 is a longitudinal sectional view showing a relationship between a throttle valve axial direction and a fuel injection direction in a comparative example.

FIG. 12 is a conceptual diagram showing a deviation of an air flow due to a direction of a throttle valve shaft of a comparative example and its influence on the directionality of fuel spray.

FIG. 13 is a cross-sectional view showing a relationship between a throttle valve axial direction and a fuel injection direction in an embodiment according to the present invention.

FIG. 14 is a longitudinal sectional view showing a relationship between a throttle valve axial direction and a fuel injection direction in an embodiment according to the present invention.

FIG. 15 is a diagram comparing the results of an investigation on the relationship between the throttle valve axial direction and ΔA / F.

FIG. 16 is a conceptual diagram illustrating a relationship between a throttle valve axial direction and a fuel injection direction according to another embodiment of the present invention.

FIG. 17 is a conceptual diagram showing a relationship between a throttle valve axial direction and a fuel injection direction of another embodiment according to the present invention.

FIG. 18 is a cross-sectional view showing a relationship between a passage outlet position of an auxiliary air system and a fuel injection direction in a comparative example.

FIG. 19 is a longitudinal sectional view showing a relationship between a passage outlet position of an auxiliary air system and a fuel injection direction in a comparative example.

FIG. 20 is a cross-sectional view showing a relationship between a passage outlet position of an auxiliary air system and a fuel injection direction in an embodiment according to the present invention.

FIG. 21 is a longitudinal sectional view showing a relationship between a passage outlet position of an auxiliary air system and a fuel injection direction in an embodiment according to the present invention.

FIG. 22 is a diagram comparing the examination results of the relationship between the position of the passage outlet of the auxiliary air system and ΔA / F.

FIG. 23 is a longitudinal sectional view showing a relationship between a passage outlet position of an auxiliary air system and a fuel injection direction according to another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 1a ... Intake port, 2 ... Intake pipe, 2b,
2c, 2d: branch intake pipe, 3: fuel injection valve, 3s: fuel injection valve drive signal, 4: throttle valve, 4a: valve shaft, 5
a, 5b: air flow, 6: throttle opening sensor, 7: intake pipe negative pressure sensor, 8: auxiliary intake pipe, 8a: passage valve, 8b
... opening, 9 ... cooling water temperature sensor, 10 ... control device, 30
... Nozzle part, 31 ... Movable valve, 32a ... First cylinder orifice, 32b ... Second cylinder orifice, 32c ... Third cylinder orifice, 190 ... Input signal, 191 ... Input circuit, 192
... A / D converter, 193 ... Central processing unit, 194 ... ROM, 195
… RAM, 196… Output circuit, 197… Control output signal

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Makoto Tamura 2520 Ojitakaba, Hitachinaka City, Ibaraki Prefecture Inside the Automotive Equipment Division of Hitachi, Ltd. (72) Inventor Mamoru Nemoto 2477 Takaba Hitachinaka City, Ibaraki Pref. Within Hitachi Car Engineering

Claims (5)

[Claims] An intake pipe having a plurality of branch intake pipes at a downstream portion and connected to an internal combustion engine, and a throttle disposed at an upstream portion of the intake pipe and controlling a flow rate of an airflow flowing through the intake pipe. A valve, and a fuel injection valve that is disposed between the branch intake pipe and the throttle valve and that injects fuel in multiple directions toward the respective branch intake pipes from injection ports arranged in a line. In the fuel injection valve, a plane including a vertical bisector of a substantially isosceles triangle having an injection port formed by each injection direction axis of the fuel injection valve as an apex is directed from the throttle valve to the branch intake pipe. An air-fuel mixture forming apparatus for an internal combustion engine, which is provided so as to also include a main streamline of the flowing air flow. 2. The air-fuel mixture formation for an internal combustion engine according to claim 1, wherein a valve axis direction of said throttle valve is disposed so as to be substantially parallel to a base direction of said substantially isosceles triangle. apparatus. 3. The intake pipe according to claim 1, wherein the intake pipe has an auxiliary intake pipe for introducing the air flow by bypassing the throttle valve, and an opening on a downstream side of the auxiliary intake pipe is provided. An air-fuel mixture forming device for an internal combustion engine, characterized in that the opening is formed in the intake pipe such that a jet direction of the air flow blown into the intake pipe from the opening substantially overlaps a direction of the vertical bisector. 4. An intake pipe having a plurality of branch intake pipes at a downstream portion and connected to an internal combustion engine, and a throttle disposed at an upstream portion of the intake pipe and controlling a flow rate of an airflow flowing through the intake pipe. A valve, and a fuel injection valve that is disposed between the branch intake pipe and the throttle valve and that injects fuel in multiple directions toward the respective branch intake pipes from injection ports arranged in a line. The fuel injection valve is disposed such that each injection direction axis of the fuel injected from the injection port substantially matches a main streamline of the air flow flowing through each of the branch intake pipes toward the internal combustion engine. An air-fuel mixture forming apparatus for an internal combustion engine, comprising: 5. An engine system using the air-fuel mixture forming device for an internal combustion engine according to claim 1.