JP3535949B2 - Multi-cylinder internal combustion engine with multi-directional fuel injection valve - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-cylinder internal combustion engine and its intake pipe structure, and more particularly to a single fuel injection valve for simultaneously injecting fuel in a plurality of directions toward a plurality of cylinders of the multi-cylinder internal combustion engine. , the throttle valve provided in the intake pipe downstream, in which relates to a multi-cylinder internal combustion institution having a multi-way fuel injection valve.

[0002]

2. Description of the Related Art An inexpensive fuel supply system for a multi-cylinder internal combustion engine is required. As an inexpensive fuel supply method, a method using a carburetor and a method of supplying fuel to a plurality of cylinders with one fuel injection valve can be considered.

In the fuel supply system using a vaporizer, the fuel is very well atomized to a particle size of about 30 μm. For this reason, air and fuel are easily mixed uniformly, and if the amount of air distributed to each cylinder is even, matching man-hours are required, but variations in the air-fuel ratio A / F of each cylinder are It can be within a predetermined value. However, the fuel supply system using a carburetor has few control elements for fuel supply, so detailed control according to operating conditions cannot be performed, and toxic exhaust gas (HC, C
It is difficult to reduce O, NOx).

Further, in a so-called single-point type fuel injection system in which a fuel injection valve is arranged upstream of a throttle valve as a system for supplying fuel to a plurality of cylinders by one fuel injection valve, fuel atomization is performed. The degree is inferior to that of the system using the carburetor, so that the wall adhering flow of the fuel in the middle of the intake passage increases and the variation in the air-fuel ratio distribution characteristic increases. Therefore, the length of the intake passage for each cylinder is changed, or a groove or a heater for promoting vaporization is provided, but in order to reduce the variation in air-fuel ratio distribution characteristics, the number of matching steps is Very many.

On the other hand, in order to realize an inexpensive fuel injection device for an internal combustion engine, a fuel injection valve capable of branch-injecting fuel in multiple directions and an intake pipe collecting portion corresponding to each cylinder downstream of the throttle valve are provided. Has been proposed to supply fuel to a plurality of cylinders with one cylinder. For example, JP-A-6
That is the method described in Japanese Patent Laid-Open No. 3-223364. In this method, since the distance from the fuel branch injection point to the internal combustion engine is relatively short, it is difficult to mix air and fuel uniformly, but fuel is distributed to each cylinder in each direction of the multidirectional fuel injection valve itself. It is understood that the air-fuel ratio A / F among the cylinders can be suppressed to be low if the amount of air distributed to the cylinders is substantially controlled by the branch fuel distribution performance to the cylinders.

Also in the above-mentioned Japanese Patent Laid-Open No. 63-223364, the amount of fuel supplied to each intake pipe is determined by the amount of injection from each injection port of the fuel injection valve, and only the variation in the diameter is the fuel between the cylinders. It only points to distribution.

On the other hand, in the internal combustion engine as a whole, by controlling the fuel supply so that the air-fuel ratio A / F in the exhaust gas detected by the O2 sensor becomes the stoichiometric air-fuel ratio, the poisonous exhaust gas ( HC, CO, NOx) is being reduced.

[0008]

However, in order to realize an inexpensive fuel injection device, a fuel injection valve for injecting fuel in multiple directions from one fuel injection valve toward a plurality of cylinders of an internal combustion engine is throttled. In the fuel injection device for the internal combustion engine provided downstream of the valve, there are large variations in the distribution characteristics of the air-fuel ratio A / F among the cylinders described above, and the stability of idle is impaired, and the toxic exhaust gas in the exhaust gas is reduced. This results in an increase and a decrease in the output of the internal combustion engine.

According to an experiment conducted by the inventor, in the system in which the fuel injection valve is arranged downstream of the throttle valve and the fuel is supplied to a plurality of cylinders by one cylinder, the fuel distributability is greatly different from that of the wall-adhered fuel. to be influenced. However, since it is very difficult to intentionally adjust the flow direction of the fuel adhering to the wall surface, it is necessary to have a structure in which the fuel does not adhere to the wall surface and can move in the intake path as freely as possible. . It was also clarified that the positional relationship of each cylinder is related to the degree of deterioration of fuel distribution.

For example, when the distribution state of the injected fuel injection flow at a specific stroke position during operation of the three-cylinder internal combustion engine is examined, the distribution state of the injected fuel flow when the inner cylinder is in the suction state is as follows: Since there are two cylinders adjacent to each other on the left and right, the amount of floating fuel located around the inside cylinder is large, and a large amount of floating fuel is sucked into the inside cylinder, and the inside The air-fuel ratio of the cylinder becomes rich.

On the other hand, since the number of cylinders located outside is only one, the amount of floating fuel around the cylinders is smaller than that of the inside cylinders, and the amount of floating fuel around the cylinders is smaller than that of the inside cylinders. The outer cylinder has a small amount of fuel suction, and the air-fuel ratio of the outer cylinder tends to be thin. Moreover, if the intake order of the outer cylinder is later than that of the inner cylinder, the floating fuel has already been sucked into the inner cylinder, and the amount of floating fuel to be sucked into the outer cylinder is insufficient.
Further, the air-fuel ratio of the outer cylinder becomes thin, resulting in a decrease.

It has also been clarified that the distribution characteristic of the air-fuel ratio A / F among the cylinders is affected not only by the positional relationship of the cylinders but also by the shape of the intake pipe. That is, since the intake pipe is L-shaped, the air flow hits the bottom surface of the L-shaped intake pipe and then flows back upstream. This means that the injected fuel is wound up on the collecting portion of the intake pipe by the flow of air.

FIG. 19 shows an example of the shape of a conventional L-shaped intake pipe.
Shown in. Since the internal combustion engine tested in the experiment has 3 cylinders, the intake branch passage 4 is also divided into 3 directions, 4A, 4B and 4C. Injection valve 6
From 66 to 66a, fuel is injected and reaches the vicinity of the intake valve 7 beyond the branch portion 4d of the intake pipe. As an experimental result, FIG. 20 shows the relationship between the suction negative pressure and the maximum difference ΔA / F in the air-fuel ratio A / F between the cylinders when the internal combustion engine speed is 2000 rpm. It can be said that the larger the A / F variation width ΔA / F is, the more uneven the fuel amount among the cylinders is. According to the experimental results, it can be seen from the magnitude of the A / F variation width ΔA / F that the fuel distribution characteristic deteriorates with the pressure change in the intake pipe. The above results show a large value of ΔA / F = 3.3 at 2000 rpm and -200 mmHg. Such deterioration of fuel distribution characteristics leads to a decrease in output of the internal combustion engine, deterioration of drivability, and increase of harmful components of exhaust gas.

Regarding the conventional example of the intake system shown in FIG.
FIG. 21 shows the result of simulation for the cause analysis of the deterioration factor of ΔA / F. Arrows 4a, 4b
Indicates the flow of air. 66a indicates the fuel injected from the injection valve 6. It can be seen from FIG. 21 that the air flow hits the bottom surface of the L-shaped intake pipe 4 and then flows back upstream as in 4a. This means that the injected fuel
This means that 66a is wound around the collecting portion of the intake pipe by the air flow 4a.

Therefore, the fuel injected aiming at the specific cylinder is returned to the gathering portion of the intake pipes, so that it is sucked during the intake stroke of the other cylinders. This leads to a decrease in output of the internal combustion engine, deterioration of drivability, and increase of harmful components of exhaust gas.

It is an object of the present invention to have an orifice capable of injecting fuel in a plurality of directions-an intake collecting section equipped with a plurality of fuel injection valves, and a branch from the intake collecting section to each cylinder of the internal combustion engine. And three intake branch paths that extend
In a multi-cylinder internal combustion engine having a structure in which intake air sucked from the intake collecting portion of the intake pipe is introduced from a direction substantially perpendicular to the injection direction of the fuel injection valve, the air-fuel ratio A / F to each cylinder is An object of the present invention is to provide a low-cost and high-performance multi-cylinder internal combustion engine by making the distribution characteristics uniform.

Another object of the present invention is to intake air of a multi-cylinder internal combustion engine having a structure in which intake air taken in from an intake collecting portion of an intake pipe is introduced from a direction substantially perpendicular to an injection direction of the fuel injection valve. It is an object of the present invention to provide an intake pipe of a multi-cylinder internal combustion engine, which has a structure in which the distribution characteristic of the air-fuel ratio A / F to each cylinder is made uniform and stable and the air-fuel ratio of each cylinder can be matched.

[0018]

The features of the present invention include a throttle body having a throttle valve, and an intake pipe connected to the throttle body for supplying a mixture of air and fuel to each cylinder of an internal combustion engine. A fuel injection valve having an orifice attached to the intake pipe and capable of injecting fuel in a plurality of directions, the intake pipe including an intake collecting portion connected to the throttle body, and the internal combustion engine. A plurality of intake branch passages extending in a substantially right-angled direction toward the intake collecting portion toward each cylinder of the intake air, and intake air is introduced from a direction substantially perpendicular to the injection direction of the fuel injection valve. In the cylinder internal combustion engine, the intake pipe extends from a bottom wall of the intake pipe to a height equal to or higher than an axial center O-O of the fuel injection valve at a branch portion from the intake collecting portion to the intake branch passage, Injected from the injection valve And a branch partition wall for distributing the fuel to each of the intake branch passages, and the height of the upper edge of the branch partition wall is continuously increased from the fuel injection valve side tip toward the internal combustion engine side tip. The wall surface on the fuel injection valve side of the intake manifold is higher, along the inflow direction of the intake air,
It is configured as a stabilizer projecting toward the branch portion with an arc or a curvature close to the arc, and the fuel injection valve side tip of the upper edge of the branch partition wall is below the lower end of the stabilizer and at the lower end of the stabilizer. It is located near the extension line.

Another feature of the present invention is that the height from the bottom surface of the intake pipe to the axial center OO of the fuel injection valve is h0,
Assuming that the height of the upper edge of the partition wall on the fuel injection valve side from the bottom surface is h1, the height ratio h1 / h0.
Is set to 1.0 or more and 2.0 or less.

Another feature of the present invention is that the angle α2 formed by the tangent line at the lower end of the stabilizer and the axial center of the fuel injection valve is set to 45 degrees or less. Another feature of the present invention resides in that the angle α1 formed by the upper edge of the branch partition wall and the axis of the fuel injection valve is set to 45 degrees or less.

Another feature of the present invention is that it has an orifice that is connected to a throttle body and is capable of injecting fuel in a plurality of directions-an intake collecting portion equipped with a plurality of fuel injection valves, and each cylinder of an internal combustion engine. A multi-cylinder internal combustion engine having a plurality of intake branch passages extending in a direction substantially perpendicular to the intake collecting portion toward the intake air, and the intake air is introduced from a direction substantially perpendicular to the injection direction of the fuel injection valve. In the intake pipe structure described above, the intake pipe is provided at a branch portion from the intake collecting portion to the intake branch passage, and an axial center OO of the fuel injection valve is provided from a bottom wall of the intake pipe.
The fuel injection valve is provided with a branch partition wall which extends to the above height and distributes the fuel injected from the fuel injection valve to each of the intake branch passages, and the height of the upper edge of the branch partition wall is the fuel injection valve. The height increases continuously from the side tip toward the internal combustion engine side tip, and the wall surface of the intake manifold on the fuel injection valve side branches along the inflow direction of the intake air with an arc or a curvature close to the arc. The fuel injection valve side tip of the upper edge of the branch wall is located below the lower end of the stabilizer and in the vicinity of the extension line of the lower end. There is an intake pipe structure.

According to the intake pipe of the present invention, the intake air that has flowed in from the vertical direction is prevented from hitting the bottom surface of the intake pipe substantially vertically by the stabilizer, and the direction is smoothly changed to the substantially horizontal direction to inject the fuel. The fuel injected from the valve flows along the spray direction. Further, the branch partition wall provided in the portion where the intake pipe branches from the intake collecting portion into the three intake branch passages surrounds just outside the fuel in a range where it does not contact the fuel injected from the fuel injection valve, It has a function of properly distributing the fuel to each intake branch passage.

As described above, according to the present invention, in the intake structure of a multi-cylinder internal combustion engine in which fuel is injected into a plurality of cylinders by a single injection valve, intake air drawn from the intake collecting portion of the intake pipe is Despite the intake structure introduced from a direction substantially perpendicular to the injection direction of the fuel injection valve, the action of the stabilizer and the branch partition wall makes it possible to make the air-fuel ratio distribution among the cylinders uniform. It is possible to obtain a low-cost multi-cylinder internal combustion engine in which a high performance equivalent to that in which a fuel injection valve is arranged in each cylinder can be obtained, and a fuel supply system and a control system are greatly simplified.

That is, according to the present invention, a single injection valve is used to inject fuel into a plurality of cylinders, and in spite of the intake structure introduced from a direction substantially perpendicular to the injection direction of the fuel injection valve, it is a multi-cylinder. The air-fuel ratio A / F between them can be made substantially uniform, or the difference in the air-fuel ratio A / F can be reduced. Since the distribution characteristic of the air-fuel ratio A / F to each cylinder is uniform and stabilized, the fluctuation of the output torque of the internal combustion engine can be suppressed low, and the drivability of the internal combustion engine can be improved. The purification rate of toxic exhaust gas (HC, CO, NOx) in the exhaust gas of an internal combustion engine largely depends on the variation of the air-fuel ratio A / F, and the purification rate of exhaust gas is greatly improved.

Further, according to the present invention, the distribution characteristic of the air-fuel ratio A / F to each cylinder can be made uniform while having a simple structure for simultaneously supplying fuel to a plurality of cylinders with one fuel injection valve. A low-cost, high-performance multi-cylinder internal combustion engine equivalent to one in which a fuel injection valve is arranged in each cylinder can be realized.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a system configuration example of a fuel injection device to which the present invention is applied, and FIG. A throttle valve 3 is provided on a throttle body 2 connected to the air cleaner 1. The internal combustion engine 5 is a three-cylinder internal combustion engine, and an intake manifold 4 is connected to an intake port of the multi-cylinder internal combustion engine 5.
A single fuel injection valve 6 for injecting fuel is arranged in the intake manifold 4. 7A and 7B are internal combustion engine 5 respectively.
The intake valve and the exhaust valve. An intake pipe negative pressure sensor 14 and a throttle opening sensor 15 are provided to detect the load state of the internal combustion engine 5. Further, in order to detect the state of the exhaust gas of the internal combustion engine 5, an O 2 sensor 11 is installed in the exhaust pipe 8.
Are arranged. Further, a cooling water temperature sensor 12 and a crank angle sensor 13 that detects the rotation speed and crank angle of the internal combustion engine 5 are arranged.

The controller 10 takes in the detection signals from the various sensors and generates a fuel injection valve drive signal based on the detection results, whereby the fuel injection valve 6 is driven.
Fuel injection control means for controlling The fuel injection valve 6 is provided with a plurality of orifices so as to inject fuel in a plurality of directions, and one injection valve is used for the intake ports (1Aa, 1Aa, 1Aa, 1Aa) of a plurality of cylinders of the internal combustion engine 5.
Fuel is simultaneously injected toward Ba, 1Ca). As a general rule, the fuel injection valve 6 operates in synchronization with the intake stroke of each cylinder.
A cylinder internal combustion engine is controlled to inject fuel only three times every two revolutions. Actually, in consideration of the distribution characteristics of air and fuel of each cylinder, that is, A / F, the fuel is controlled to be injected only 1 to 3 times per cycle of the internal combustion engine. The valve opening timing of 6 does not necessarily correspond to the intake stroke of each cylinder. The distribution performance is slightly inferior, but 2
The injection may be performed once or twice in rotation.

The controller 10 further includes an ignition coil 1
6, control means for controlling the ISC valve 21, the fuel pump 31, etc. are also provided.

Reference numeral 30 denotes a fuel tank, and the fuel is sucked by the fuel pump 31 and reaches the fuel injection valve 6 through the fuel pipe 33. Further, a pressure regulator 32 for adjusting the fuel pressure to a constant level and a damper 34 for reducing the pressure fluctuation of the fuel are provided. The appropriate injection amount of the fuel injection valve 6 is calculated and determined by the control unit 10 based on inputs from various sensors. As will be described later, the fuel injection valve 6 is provided with one or more orifices capable of injecting fuel in a plurality of directions, and not one injection valve for each cylinder of the internal combustion engine 5 but one injection valve. Therefore, a plurality of injection ports are provided to inject fuel into each branch pipe.

FIG. 2 and FIG. 3 show a front view and an exploded perspective view, respectively, of a partial cross section of an intake system according to an embodiment of the present invention. The intake pipe 4 connected to the wake of the throttle body 2 via the gasket 9 is bent in the shape of "L" near the position where the fuel injection valve 6 is attached, and extends linearly to each cylinder of the internal combustion engine 5. Intake branch paths 4A, 4B, and 4C are branched. As described above, the intake pipe 4 includes the intake collecting portion 4M in which the fuel injection valve 6 and the pressure regulator 32 are mounted, and the three intake branch passages 4A and 4A that branch in accordance with the number of cylinders of the internal combustion engine 5.
It is divided into B and 4C.

The fuel supplied from the fuel pump 31 through the fuel pipe 33, the damper 34 through the connection passage 35.
The pressure fluctuation of the fuel is alleviated by this damper. The fuel further reaches the fuel injection valve 6 via a fuel passage 36 provided in the intake collecting portion 4M and a fuel passage 37 provided in the intake collecting portion 4M. A pressure regulator 32 is connected to the fuel injection valve 6 via a fuel connecting pipe 38. After the pressure of the fuel is adjusted to a predetermined value by the pressure regulator 32, the fuel is returned to the fuel tank 30 through a return passage 39. Be done. Since the fuel passages 36 and 37 are provided directly in the intake collecting portion 4M, the fuel injection valve 6
A fuel connecting pipe for connecting the pressure regulator 32 and the damper 34 is unnecessary.

FIG. 4 is a vertical sectional view of the intake pipe 4. The intake pipe 4 includes an intake collecting portion 4M and intake branch passages 4A, 4B, 4C. The intake collecting portion 4M has a flange formed on the upper surface thereof, and an opening 60 for mounting the fuel injection valve 6 through the O-ring 61 is provided on the wall on the side opposite to the intake branch passage, and the walls on the left and right sides thereof are provided. , The fuel passage 37 for connecting the pressure regulator 32, and the damper 3
And a fuel passage 36 for connecting the four.
The intake branch passages 4A, 4B, and 4C extend substantially linearly from the orifice position of the fuel injection valve 6 of the intake collecting portion 4M to the vicinity of the intake valve 7 of the internal combustion engine 5 in either a vertical or horizontal cross section. While branching radially.

FIG. 5 is an enlarged view of the vicinity of the nozzle of the fuel injection valve 6 according to the present invention, and FIG. 6 shows three orifices 6.
5 shows the fuel spray direction according to No. 5. The main body of the fuel injection valve 6 is a side feed type in which fuel is introduced from the side portion of the injection valve main body. The fuel that has entered the fuel injection valve 6 has three orifices 65 provided in a movable valve 63 and a nozzle 64 that move up and down by an electromagnetic force, that is, a first cylinder orifice 65a, a second cylinder orifice 65b, and a third cylinder. A metering orifice 65c measures and jets. Direction of the three orifices 65a, 65b, 65c provided in the fuel injection valve 6 in order to make the fuel distribution uniform (θ1)
Is configured to face the intake port of each cylinder of the internal combustion engine 5.

In other words, the fuel injected from the orifice 65 of the fuel injection valve 6 in three directions at intervals of θ1 and propagating while spreading at an angle of θ2 first collides with the wall surface of the intake passage at a position where the intake air of the internal combustion engine 5 is inhaled. It is desirable to be near the valve 7A.

Here, the detailed structure of the intake pipe 4 of the present invention will be described with reference to FIGS. 7 to 9. FIG. 7 shows A- of FIG.
A sectional view, FIG. 8 is a plan view of a main portion of an intake pipe, and FIG. 9 is an enlarged view of an intake branch portion.

In the intake passage in the intake pipe 4, the axis O--O of the fuel injection valve 6 has a slight inclination angle with respect to the horizontal plane and extends in a direction substantially along the center line of the intake branch passage 4B. There is. As shown in FIGS. 7 and 8, a stabilizer 4g is formed on the vertical wall of the intake collecting portion 4M on the side of the fuel injection valve and extends to the branch portion with an arc of radius R or a curvature close to the arc.

The tip portion 4h of the stabilizer 4g reaches the edge of the opening 60 for mounting the fuel injection valve 6. The intake air that has flowed in from the vertical direction is prevented from hitting the bottom surface of the intake pipe 4 substantially vertically by the stabilizer 4g, and smoothly changes its direction to a substantially horizontal direction, and the fuel injection valve 6
Flows along the spray direction of the fuel injected from. Also,
The bottom surface 4n of the intake pipe 4 also has a slight inclination angle along the axis O-O of the fuel injection valve 6, and contributes to making the inflow directions of the intake air and the fuel coincide with each other.

On the other hand, in the portion where the intake pipe 4 branches from the intake collecting portion 4M into the three intake branch passages 4A, 4B and 4C, the fuel injected from the fuel injection valve 6 is properly distributed to each intake branch passage. An elongated branch partition wall 4d is formed for this purpose.
The upper edge of the branch partition wall 4d continuously increases in height from the fuel injection valve side tip 4j to the internal combustion engine side tip 4k.

Fuel injection valve side tip 4j of the upper edge of the branch partition wall
Is located above the axis O-O of the fuel injection valve 6 and below the tip 4h of the stabilizer 4g and in the vicinity of the extension of the tip 4h. As shown in FIG. 10, the controller 10 includes an input circuit 191, an A / D
Conversion unit 192, central processing unit 193, ROM 194, RA
It is composed of a computer including an M195 and an output circuit 196. The input circuit 191, the input signal 19
0 (for example, a signal from the cooling water temperature sensor 9, the throttle opening sensor 6 and the like) is received, noise components are removed from the signal, and the signal is output to the A / D converter 192. is there. The A / D conversion unit 192 is for A / D converting the signal and outputting it to the central processing unit 193. The central processing unit 193 takes in the A / D conversion result and executes a fuel injection control program stored in a medium such as the ROM 194 or a predetermined control program for other control, thereby performing the above-mentioned control and diagnosis. It has a function to execute. 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 the output circuit 196 and used for controlling the fuel injection valve 6 and the like. It is composed. However, the configuration of the controller 10 is not limited to this.

FIG. 11 is a time chart for explaining an example of fuel injection timing. In the example of FIG. 11, the fuel is injected from one injection valve 6 to three cylinders (1A, 1B, 1C) at the same time only three times in two revolutions of the internal combustion engine. The fuel injection width Tin is a constant value (Tin1 = Tin2
= Tin3). The fuel injection timing θinj is
Position of each intake stroke of three cylinders, θinj1 = 120 °,
θinj2 = 360 ° and θinj3 = 600 °, and fuel is injected from the three orifices 65a, 65b, and 65c toward each cylinder at the same time. The fuel injected from the fuel injection valve 6 to the intake passage is supplied to the internal combustion engine 5 while being mixed with intake air in the intake passage.

The intake pipe 4 of the present invention has three intake branch passages as shown in FIG. 12 in order to prevent the fuel from adhering to the wall surface of the intake pipe 4 and causing a wall flow to disturb the distribution of the fuel. 4A,
4B and 4C extend in a substantially straight line. Therefore, in the normal operating state, the fuel 66a injected from the orifice of the fuel injection valve 6 first contacts the wall surface near the intake port of the internal combustion engine. In other words, in a normal operating state, the fuel injected from the orifice does not come into contact with the wall surface of the intake pipe 4 on the way and reaches each intake port of the internal combustion engine 5. As a result, the wall surface flow of the fuel is limited, and the distribution amount of fuel to the three cylinders is determined mainly by the measurement by the orifice of the injection valve regardless of the configuration of each intake path, and the air-fuel ratio distribution between the cylinders is determined. It can be homogenized with high accuracy.

In order to prevent the generation of wall flow of fuel,
The shape of the branch partition wall 4d is also important. Since the branch partition wall 4d is provided for the purpose of improving the distribution of the fuel injected from the fuel injection valve 6, it is preferable to bring it as close to the fuel injection valve as possible. However, when the fuel that spreads while spreading at the angle θ2 comes into contact with the branching partition wall 4d, the distribution characteristics are deteriorated due to the generation of the wall surface flow and the disturbance of the fuel flow. Therefore, the branching partition wall 4d extends as far as possible to the upstream side, that is, to a position as close to the fuel injection valve as possible so as to guide the fuel 66a to each cylinder while wrapping the fuel 66a in a range not in contact with the spread angle θ2 of the fuel 66a ejected from the fuel injection valve 6. Therefore, it is better to make it elongated.

When the intake pipe is L-shaped, the distribution characteristic of the air-fuel ratio A / F among the cylinders is affected not only by the positional relationship of the cylinders but also by the shape of the intake pipe as described above. receive. That is, there is a phenomenon that the intake air hits the bottom surface of the L-shaped intake pipe and then flows back to the upstream, so the injected fuel is wound up by the air flow to the intake collecting portion of the intake pipe, The fuel injected aiming at
It may be inhaled during the intake stroke of another cylinder.

On the other hand, in the present invention, in order to improve the fuel and air distribution characteristics of the L-shaped intake pipe, the stabilizer 4g and the branch partition wall 4d are provided. Partition wall of the present invention
The upper edge of 4d continuously rises from the fuel injection valve side tip 4j toward the internal combustion engine side tip 4k so as to face the inflowing intake air.

In FIG. 13, the height from the bottom surface 4n of the intake pipe 4 to the axial center OO of the orifice of the fuel injection valve 6 is h.
When the height from the bottom surface of the intake pipe 4 at the fuel injection valve side tip 4j of the upper edge of the partition wall 4d is set to h1, the height ratio h
FIG. 14 shows the relationship between 1 / h0 and the variation ΔA / F of the air-fuel ratio A / F, which was obtained by experiment. If the height h1 is too low compared to h0, it becomes difficult for fuel to be separated into each intake branch passage, and Δ
A / F tends to increase. From FIG. 14, in order to keep ΔA / F at the allowable value, it is preferable that the height ratio h1 / h0 be 1.0 or more.

Next, FIG. 15 shows the relationship between the height ratio h1 / h0 and the output PS of the internal combustion engine, obtained by an experiment.
From the experimental results, when the height h1 is too low compared to h0, the distribution characteristic of fuel to each cylinder is poor, and the output PS of the internal combustion engine tends to decrease. On the other hand, if the height ratio h1 / h0 is too large, the intake resistance due to the partition wall 4d increases, and it becomes difficult for air to flow into the central intake branch passage 4B in particular, and the output PS of the internal combustion engine decreases. There is a tendency. Therefore,
It can be seen that it is desirable that the height ratio h1 / h0 be 0.75 or more and 2.0 or less.

From the results of FIGS. 14 and 15, the height ratio h1
/ H0 is preferably 1.0 or more and 2.0 or less.

Next, the tip portion of the stabilizer 4g shown in FIG.
The angle between the tangent line at 4h and the axis of the fuel injection valve 6 is α2
Then, the relationship between α2 and the variation ΔA / F of the air-fuel ratio A / F is obtained by an experiment in FIG. If α2 is too large, it becomes close to the conventional one shown in FIG. 21, the distribution characteristic of the fuel deteriorates, and ΔA / F tends to increase.
From the experimental results in FIG. 16, to keep ΔA / F at the allowable value, α2
Is preferably 45 degrees or less and a relatively gentle inclination angle.

Further, the upper edge of the branch partition wall 4d and the fuel injection valve 6
It is preferable that α1 + α2 ≈ less than 90 degrees, where α1 is the angle between the orifice and the axis O-O. In other words, α1 is also preferably set to a relatively gentle inclination angle of 45 degrees or less. FIG. 17 shows the simulation result of the air flow by the intake system of the present invention. 66a indicates the fuel injected from the injection valve 6. Air flow is flowing back to the upstream after the collision members 4i, not wound up at a set portion Nima of the intake pipe, not affect the injected fuel 66a. Therefore, the fuel injected aiming at the specific cylinder is not taken in during the intake stroke of the other cylinders, and the fuel distribution can be improved.

FIG. 18 shows the experimental result for confirming the effect of the intake pipe 4 of the present invention. FIG. 18 shows the maximum deviation ΔA / F of the variation in the air-fuel ratio A / F between the cylinders when the internal combustion engine speed is 2000 rpm. According to the experimental results, it can be seen that the fuel distribution characteristic is significantly improved despite the change in the intake pipe pressure. In other words, the value of ΔA / F is
Compared to the conventional 3.3 shown in 0, it is reduced to 1.0 or less. By improving the fuel distribution characteristics as described above, it is possible to increase the output of the internal combustion engine and reduce the harmful components of the exhaust gas.

[0051]

According to the present invention, in the intake structure of a multi-cylinder internal combustion engine in which a single injection valve injects fuel into a plurality of cylinders, the intake air sucked from the intake collecting portion of the intake pipe is Despite the intake structure introduced from a direction substantially perpendicular to the injection direction of the fuel injection valve, the air-fuel ratio distribution among the cylinders can be made uniform, so that the fuel injection valve is arranged in each cylinder. It is possible to obtain a low-cost multi-cylinder internal combustion engine that can achieve equivalent high performance, improve operability, and greatly simplify the fuel supply system and control system.

That is, fuel is injected into a plurality of cylinders with a single injection valve, and despite the intake structure introduced from a direction substantially perpendicular to the injection direction of the fuel injection valve, the air-fuel ratio to each cylinder is increased. Since the A / F distribution characteristic is uniform and stabilized, the fluctuation of the output torque of the internal combustion engine can be suppressed low, and the drivability of the internal combustion engine can be improved. Further, the purification rate of toxic exhaust gas (HC, CO, NOx) in the exhaust gas of the internal combustion engine greatly depends on the air-fuel ratio A / F, and the purification rate of exhaust gas is greatly improved.

Further, according to the present invention, the distribution characteristic of the air-fuel ratio A / F to each cylinder can be made uniform while having a simple structure in which fuel is simultaneously supplied to a plurality of cylinders by one fuel injection valve. A low-cost, high-performance multi-cylinder internal combustion engine equivalent to one in which a fuel injection valve is arranged in each cylinder can be realized.

[Brief description of drawings]

FIG. 1 is a diagram showing a system configuration example of a multi-cylinder internal combustion engine provided with an intake structure of the present invention.

FIG. 2 is a partial cross-sectional view of an intake structure of the multi-cylinder internal combustion engine of FIG.

3 is an exploded perspective view of an intake structure of the multi-cylinder internal combustion engine of FIG. 1. FIG.

FIG. 4 is a vertical sectional view of the intake pipe of FIG.

5 is a longitudinal sectional view of a main part showing an example of an orifice part of the fuel injection valve of FIG.

6 is a functional explanatory diagram of an orifice of the fuel injection valve of FIG. 1. FIG.

FIG. 7 is a side view taken along the line AA of FIG.

FIG. 8 is a plan view of a main part of the intake pipe of FIG.

FIG. 9 is an enlarged view of a branch partition portion of the intake pipe.

FIG. 10 is a diagram showing a configuration example of the controller of FIG. 1.

11 is a time chart explaining an example of fuel injection timing in the controller of FIG.

FIG. 12 is a transverse cross-sectional view for explaining the structure of an intake branch passage according to the present invention.

FIG. 13 is a vertical cross-sectional view for explaining the structure of an intake branch passage according to the present invention.

FIG. 14 is a diagram obtained by an experiment to determine the relationship between the height h1 of the branch partition wall in FIG. 13 and ΔA / F.

FIG. 15 is a diagram in which the relationship between the height h1 of the branch partition wall in FIG. 13 and the output is obtained by an experiment.

16 is a diagram obtained by an experiment for a relationship between ΔA / F and an angle α2 formed by the tangent line at the tip of the stabilizer in FIG. 13 and the axis of the fuel injection valve.

FIG. 17 is a diagram showing a simulation result of an air flow by the intake system of the present invention.

FIG. 18 is a diagram showing experimental results for confirming effects of the intake pipe of the present invention.

FIG. 19 is a vertical cross-sectional view for explaining the configuration of a conventional L-type intake branch passage.

20 is a diagram showing a simulation result of an air flow by the intake system of FIG.

FIG. 21 is a diagram showing experimental results for confirming the effects of the intake pipe of FIG.

[Explanation of symbols]

1 ... Air cleaner, 2 ... Throttle body, 3 ... Throttle valve, 4 ... Intake pipe, 4A, 4B, 4C ... Intake branch passage, 4d ... Branch partition wall, 4g ... Stabilizer, 4M ... Intake collecting section, 5 ... Internal combustion engine , 6 ... Fuel injection valve, 7A ... Intake valve,
7B ... Exhaust pipe, 10 ... Controller, 11 ... O2 sensor, 63 ... Movable valve, 64 ... Nozzle, 65 ... Injection orifice, 65a ... First cylinder orifice, 65b ... Second cylinder orifice, 65c ... Third cylinder Orifice,

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Makoto Tamura 2520 Takaba, Hitachinaka City, Ibaraki Hitachi Ltd. Automotive Equipment Division, Hitachi, Ltd. (72) Inventor Hiroyuki Niwa 300 Tsukamachi, Hamamatsu, Shizuoka Suzuki Suzuki Co., Ltd. (72) Inventor Shuichi Yamane, 300, Takatsuka-cho, Hamamatsu-shi, Shizuoka, Suzuki stock company (72) Inventor, Mitsuyasu Yamamoto, 300, Takatsuka-machi, Hamamatsu-shi, Shizuoka (56) Reference JP-A-9 −209879 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) F02M 69/00 350 F02M 69/04 F02M 35/10 102

Claims (3)

(57) [Claims] 1. A throttle body having a throttle valve, an intake pipe connected to the throttle body for supplying a mixture of air and fuel to each cylinder of an internal combustion engine, and the intake pipe is formed in an L shape. The intake manifold connected to the throttle body and the intake branch passage formed from the intake manifold toward each cylinder. The intake manifold includes a plurality of fuel injectors capable of injecting fuel toward each cylinder. A number of orifices and a fuel injection valve, and a wall on the side where the fuel injection valve is mounted, which protrudes toward the branch passage side with an arc or a curvature close to the arc along the inflow direction of the intake air from the intake collecting portion. A multi-cylinder internal combustion engine configured to inject fuel from a direction substantially perpendicular to an intake air inflow direction of the intake air collecting portion, The intake pipe has an axial center (O-O) of the fuel injection valve from the bottom surface of the intake pipe formed in an L shape from the intake collecting portion.
A branch partition wall for distributing the fuel injected from the fuel injection valve to each of the intake branch passages, which extends to the above height,
The upper edge of the branch partition wall is formed continuously from the tip of the fuel injection valve side toward the internal combustion engine side, and the height from the bottom surface of the intake pipe to the axial center of the orifice of the fuel injection valve is h.
_When the height from the bottom surface of the tip of the fuel injection valve on the upper edge of the branch partition wall is h ₁ , the height ratio h _{1 is}
A multi-cylinder internal combustion engine equipped with a multi-directional fuel injection valve, characterized in that it is configured by an intake pipe provided with a branch partition wall where / h ₀ is 1.0 ≦ h ₁ / h ₀ ≦ 2.0. _{2. The} angle α ₂ between the tangent line at the tip of the stabilizer protruding toward the branch passage and the axial center of the orifice of the fuel injection valve is set to the bottom surface of the intake pipe according to claim 1.
On the other hand, a multi-cylinder internal combustion engine provided with a multi-directional fuel injection valve, which is 45 degrees or less on a vertical plane . 3. The angle α ₁ between the upper edge of the branch wall and the axis of the orifice of the fuel injection valve according to claim 2.
Is 45 degrees or less on a plane perpendicular to the bottom surface of the intake pipe, a multi-cylinder internal combustion engine having a multi-directional fuel injection valve.